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aeed109950b2c8e1c8ff42e8545cd7f4378b718b
apache/server/mpm/prefork/prefork.c
André Malo aeed109950 the eight space tabs are harassing me. 
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git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@103348 13f79535-47bb-0310-9956-ffa450edef68
2004-04-11 23:55:10 +00:00

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/* Copyright 1999-2004 The Apache Software Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "apr.h"
#include "apr_portable.h"
#include "apr_strings.h"
#include "apr_thread_proc.h"
#include "apr_signal.h"
#define APR_WANT_STDIO
#define APR_WANT_STRFUNC
#include "apr_want.h"
#if APR_HAVE_UNISTD_H
#include <unistd.h>
#endif
#if APR_HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#define CORE_PRIVATE
#include "ap_config.h"
#include "httpd.h"
#include "mpm_default.h"
#include "http_main.h"
#include "http_log.h"
#include "http_config.h"
#include "http_core.h" /* for get_remote_host */
#include "http_connection.h"
#include "scoreboard.h"
#include "ap_mpm.h"
#include "unixd.h"
#include "mpm_common.h"
#include "ap_listen.h"
#include "ap_mmn.h"
#include "apr_poll.h"
#ifdef HAVE_BSTRING_H
#include <bstring.h> /* for IRIX, FD_SET calls bzero() */
#endif
#ifdef HAVE_TIME_H
#include <time.h>
#endif
#ifdef HAVE_SYS_PROCESSOR_H
#include <sys/processor.h> /* for bindprocessor() */
#endif
#include <signal.h>
#include <sys/times.h>
/* Limit on the total --- clients will be locked out if more servers than
* this are needed. It is intended solely to keep the server from crashing
* when things get out of hand.
*
* We keep a hard maximum number of servers, for two reasons --- first off,
* in case something goes seriously wrong, we want to stop the fork bomb
* short of actually crashing the machine we're running on by filling some
* kernel table. Secondly, it keeps the size of the scoreboard file small
* enough that we can read the whole thing without worrying too much about
* the overhead.
*/
#ifndef DEFAULT_SERVER_LIMIT
#define DEFAULT_SERVER_LIMIT 256
#endif
/* Admin can't tune ServerLimit beyond MAX_SERVER_LIMIT. We want
* some sort of compile-time limit to help catch typos.
*/
#ifndef MAX_SERVER_LIMIT
#define MAX_SERVER_LIMIT 200000
#endif
#ifndef HARD_THREAD_LIMIT
#define HARD_THREAD_LIMIT 1
#endif
/* config globals */
int ap_threads_per_child=0; /* Worker threads per child */
static apr_proc_mutex_t *accept_mutex;
static int ap_daemons_to_start=0;
static int ap_daemons_min_free=0;
static int ap_daemons_max_free=0;
static int ap_daemons_limit=0; /* MaxClients */
static int server_limit = DEFAULT_SERVER_LIMIT;
static int first_server_limit;
static int changed_limit_at_restart;
static int mpm_state = AP_MPMQ_STARTING;
static ap_pod_t *pod;
/*
* The max child slot ever assigned, preserved across restarts. Necessary
* to deal with MaxClients changes across AP_SIG_GRACEFUL restarts. We
* use this value to optimize routines that have to scan the entire scoreboard.
*/
int ap_max_daemons_limit = -1;
server_rec *ap_server_conf;
/* one_process --- debugging mode variable; can be set from the command line
* with the -X flag. If set, this gets you the child_main loop running
* in the process which originally started up (no detach, no make_child),
* which is a pretty nice debugging environment. (You'll get a SIGHUP
* early in standalone_main; just continue through. This is the server
* trying to kill off any child processes which it might have lying
* around --- Apache doesn't keep track of their pids, it just sends
* SIGHUP to the process group, ignoring it in the root process.
* Continue through and you'll be fine.).
*/
static int one_process = 0;
static apr_pool_t *pconf; /* Pool for config stuff */
static apr_pool_t *pchild; /* Pool for httpd child stuff */
static pid_t ap_my_pid; /* it seems silly to call getpid all the time */
static pid_t parent_pid;
#ifndef MULTITHREAD
static int my_child_num;
#endif
ap_generation_t volatile ap_my_generation=0;
#ifdef TPF
int tpf_child = 0;
char tpf_server_name[INETD_SERVNAME_LENGTH+1];
#endif /* TPF */
static int die_now = 0;
#ifdef GPROF
/*
* change directory for gprof to plop the gmon.out file
* configure in httpd.conf:
* GprofDir $RuntimeDir/ -> $ServerRoot/$RuntimeDir/gmon.out
* GprofDir $RuntimeDir/% -> $ServerRoot/$RuntimeDir/gprof.$pid/gmon.out
*/
static void chdir_for_gprof(void)
{
core_server_config *sconf =
ap_get_module_config(ap_server_conf->module_config, &core_module);
char *dir = sconf->gprof_dir;
const char *use_dir;
if(dir) {
apr_status_t res;
char buf[512];
int len = strlen(sconf->gprof_dir) - 1;
if(*(dir + len) == '%') {
dir[len] = '\0';
apr_snprintf(buf, sizeof(buf), "%sgprof.%d", dir, (int)getpid());
}
else {
buf[0] = '\0';
}
use_dir = ap_server_root_relative(pconf, buf[0] ? buf : dir);
res = apr_dir_make(use_dir,
APR_UREAD | APR_UWRITE | APR_UEXECUTE |
APR_GREAD | APR_GEXECUTE |
APR_WREAD | APR_WEXECUTE, pconf);
if(res != APR_SUCCESS && !APR_STATUS_IS_EEXIST(res)) {
ap_log_error(APLOG_MARK, APLOG_ERR, res, ap_server_conf,
"gprof: error creating directory %s", dir);
}
}
else {
use_dir = ap_server_root_relative(pconf, DEFAULT_REL_RUNTIMEDIR);
}
chdir(use_dir);
}
#else
#define chdir_for_gprof()
#endif
/* XXX - I don't know if TPF will ever use this module or not, so leave
* the ap_check_signals calls in but disable them - manoj */
#define ap_check_signals()
/* a clean exit from a child with proper cleanup */
static void clean_child_exit(int code) __attribute__ ((noreturn));
static void clean_child_exit(int code)
{
mpm_state = AP_MPMQ_STOPPING;
if (pchild) {
apr_pool_destroy(pchild);
}
ap_mpm_pod_close(pod);
chdir_for_gprof();
exit(code);
}
static void accept_mutex_on(void)
{
apr_status_t rv = apr_proc_mutex_lock(accept_mutex);
if (rv != APR_SUCCESS) {
const char *msg = "couldn't grab the accept mutex";
if (ap_my_generation !=
ap_scoreboard_image->global->running_generation) {
ap_log_error(APLOG_MARK, APLOG_DEBUG, rv, NULL, msg);
clean_child_exit(0);
}
else {
ap_log_error(APLOG_MARK, APLOG_EMERG, rv, NULL, msg);
exit(APEXIT_CHILDFATAL);
}
}
}
static void accept_mutex_off(void)
{
apr_status_t rv = apr_proc_mutex_unlock(accept_mutex);
if (rv != APR_SUCCESS) {
const char *msg = "couldn't release the accept mutex";
if (ap_my_generation !=
ap_scoreboard_image->global->running_generation) {
ap_log_error(APLOG_MARK, APLOG_DEBUG, rv, NULL, msg);
/* don't exit here... we have a connection to
* process, after which point we'll see that the
* generation changed and we'll exit cleanly
*/
}
else {
ap_log_error(APLOG_MARK, APLOG_EMERG, rv, NULL, msg);
exit(APEXIT_CHILDFATAL);
}
}
}
/* On some architectures it's safe to do unserialized accept()s in the single
* Listen case. But it's never safe to do it in the case where there's
* multiple Listen statements. Define SINGLE_LISTEN_UNSERIALIZED_ACCEPT
* when it's safe in the single Listen case.
*/
#ifdef SINGLE_LISTEN_UNSERIALIZED_ACCEPT
#define SAFE_ACCEPT(stmt) do {if (ap_listeners->next) {stmt;}} while(0)
#else
#define SAFE_ACCEPT(stmt) do {stmt;} while(0)
#endif
AP_DECLARE(apr_status_t) ap_mpm_query(int query_code, int *result)
{
switch(query_code){
case AP_MPMQ_MAX_DAEMON_USED:
*result = ap_daemons_limit;
return APR_SUCCESS;
case AP_MPMQ_IS_THREADED:
*result = AP_MPMQ_NOT_SUPPORTED;
return APR_SUCCESS;
case AP_MPMQ_IS_FORKED:
*result = AP_MPMQ_DYNAMIC;
return APR_SUCCESS;
case AP_MPMQ_HARD_LIMIT_DAEMONS:
*result = server_limit;
return APR_SUCCESS;
case AP_MPMQ_HARD_LIMIT_THREADS:
*result = HARD_THREAD_LIMIT;
return APR_SUCCESS;
case AP_MPMQ_MAX_THREADS:
*result = 0;
return APR_SUCCESS;
case AP_MPMQ_MIN_SPARE_DAEMONS:
*result = ap_daemons_min_free;
return APR_SUCCESS;
case AP_MPMQ_MIN_SPARE_THREADS:
*result = 0;
return APR_SUCCESS;
case AP_MPMQ_MAX_SPARE_DAEMONS:
*result = ap_daemons_max_free;
return APR_SUCCESS;
case AP_MPMQ_MAX_SPARE_THREADS:
*result = 0;
return APR_SUCCESS;
case AP_MPMQ_MAX_REQUESTS_DAEMON:
*result = ap_max_requests_per_child;
return APR_SUCCESS;
case AP_MPMQ_MAX_DAEMONS:
*result = server_limit;
return APR_SUCCESS;
case AP_MPMQ_MPM_STATE:
*result = mpm_state;
return APR_SUCCESS;
}
return APR_ENOTIMPL;
}
#if defined(NEED_WAITPID)
/*
Systems without a real waitpid sometimes lose a child's exit while waiting
for another. Search through the scoreboard for missing children.
*/
int reap_children(int *exitcode, apr_exit_why_e *status)
{
int n, pid;
for (n = 0; n < ap_max_daemons_limit; ++n) {
if (ap_scoreboard_image->servers[n][0].status != SERVER_DEAD &&
kill((pid = ap_scoreboard_image->parent[n].pid), 0) == -1) {
ap_update_child_status_from_indexes(n, 0, SERVER_DEAD, NULL);
/* just mark it as having a successful exit status */
*status = APR_PROC_EXIT;
*exitcode = 0;
return(pid);
}
}
return 0;
}
#endif
/*****************************************************************
* Connection structures and accounting...
*/
static void just_die(int sig)
{
clean_child_exit(0);
}
/* volatile just in case */
static int volatile shutdown_pending;
static int volatile restart_pending;
static int volatile is_graceful;
static void sig_term(int sig)
{
if (shutdown_pending == 1) {
/* Um, is this _probably_ not an error, if the user has
* tried to do a shutdown twice quickly, so we won't
* worry about reporting it.
*/
return;
}
shutdown_pending = 1;
}
/* restart() is the signal handler for SIGHUP and AP_SIG_GRACEFUL
* in the parent process, unless running in ONE_PROCESS mode
*/
static void restart(int sig)
{
if (restart_pending == 1) {
/* Probably not an error - don't bother reporting it */
return;
}
restart_pending = 1;
is_graceful = (sig == AP_SIG_GRACEFUL);
}
static void set_signals(void)
{
#ifndef NO_USE_SIGACTION
struct sigaction sa;
#endif
if (!one_process) {
ap_fatal_signal_setup(ap_server_conf, pconf);
}
#ifndef NO_USE_SIGACTION
sigemptyset(&sa.sa_mask);
sa.sa_flags = 0;
sa.sa_handler = sig_term;
if (sigaction(SIGTERM, &sa, NULL) < 0)
ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, "sigaction(SIGTERM)");
#ifdef SIGINT
if (sigaction(SIGINT, &sa, NULL) < 0)
ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, "sigaction(SIGINT)");
#endif
#ifdef SIGXCPU
sa.sa_handler = SIG_DFL;
if (sigaction(SIGXCPU, &sa, NULL) < 0)
ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, "sigaction(SIGXCPU)");
#endif
#ifdef SIGXFSZ
sa.sa_handler = SIG_DFL;
if (sigaction(SIGXFSZ, &sa, NULL) < 0)
ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, "sigaction(SIGXFSZ)");
#endif
#ifdef SIGPIPE
sa.sa_handler = SIG_IGN;
if (sigaction(SIGPIPE, &sa, NULL) < 0)
ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, "sigaction(SIGPIPE)");
#endif
/* we want to ignore HUPs and AP_SIG_GRACEFUL while we're busy
* processing one
*/
sigaddset(&sa.sa_mask, SIGHUP);
sigaddset(&sa.sa_mask, AP_SIG_GRACEFUL);
sa.sa_handler = restart;
if (sigaction(SIGHUP, &sa, NULL) < 0)
ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, "sigaction(SIGHUP)");
if (sigaction(AP_SIG_GRACEFUL, &sa, NULL) < 0)
ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, "sigaction(" AP_SIG_GRACEFUL_STRING ")");
#else
if (!one_process) {
#ifdef SIGXCPU
apr_signal(SIGXCPU, SIG_DFL);
#endif /* SIGXCPU */
#ifdef SIGXFSZ
apr_signal(SIGXFSZ, SIG_DFL);
#endif /* SIGXFSZ */
}
apr_signal(SIGTERM, sig_term);
#ifdef SIGHUP
apr_signal(SIGHUP, restart);
#endif /* SIGHUP */
#ifdef AP_SIG_GRACEFUL
apr_signal(AP_SIG_GRACEFUL, restart);
#endif /* AP_SIG_GRACEFUL */
#ifdef SIGPIPE
apr_signal(SIGPIPE, SIG_IGN);
#endif /* SIGPIPE */
#endif
}
/*****************************************************************
* Child process main loop.
* The following vars are static to avoid getting clobbered by longjmp();
* they are really private to child_main.
*/
static int requests_this_child;
static int num_listensocks = 0;
int ap_graceful_stop_signalled(void)
{
/* not ever called anymore... */
return 0;
}
static void child_main(int child_num_arg)
{
apr_pool_t *ptrans;
apr_allocator_t *allocator;
apr_status_t status;
int i;
ap_listen_rec *lr;
apr_pollset_t *pollset;
ap_sb_handle_t *sbh;
apr_bucket_alloc_t *bucket_alloc;
int last_poll_idx = 0;
mpm_state = AP_MPMQ_STARTING; /* for benefit of any hooks that run as this
* child initializes
*/
my_child_num = child_num_arg;
ap_my_pid = getpid();
requests_this_child = 0;
ap_fatal_signal_child_setup(ap_server_conf);
/* Get a sub context for global allocations in this child, so that
* we can have cleanups occur when the child exits.
*/
apr_allocator_create(&allocator);
apr_allocator_max_free_set(allocator, ap_max_mem_free);
apr_pool_create_ex(&pchild, pconf, NULL, allocator);
apr_allocator_owner_set(allocator, pchild);
apr_pool_create(&ptrans, pchild);
apr_pool_tag(ptrans, "transaction");
/* needs to be done before we switch UIDs so we have permissions */
ap_reopen_scoreboard(pchild, NULL, 0);
status = apr_proc_mutex_child_init(&accept_mutex, ap_lock_fname, pchild);
if (status != APR_SUCCESS) {
ap_log_error(APLOG_MARK, APLOG_EMERG, status, ap_server_conf,
"Couldn't initialize cross-process lock in child "
"(%s) (%d)", ap_lock_fname, ap_accept_lock_mech);
clean_child_exit(APEXIT_CHILDFATAL);
}
if (unixd_setup_child()) {
clean_child_exit(APEXIT_CHILDFATAL);
}
ap_run_child_init(pchild, ap_server_conf);
ap_create_sb_handle(&sbh, pchild, my_child_num, 0);
(void) ap_update_child_status(sbh, SERVER_READY, (request_rec *) NULL);
/* Set up the pollfd array */
/* ### check the status */
(void) apr_pollset_create(&pollset, num_listensocks, pchild, 0);
for (lr = ap_listeners, i = num_listensocks; i--; lr = lr->next) {
apr_pollfd_t pfd = { 0 };
pfd.desc_type = APR_POLL_SOCKET;
pfd.desc.s = lr->sd;
pfd.reqevents = APR_POLLIN;
pfd.client_data = lr;
/* ### check the status */
(void) apr_pollset_add(pollset, &pfd);
}
mpm_state = AP_MPMQ_RUNNING;
bucket_alloc = apr_bucket_alloc_create(pchild);
while (!die_now) {
conn_rec *current_conn;
void *csd;
/*
* (Re)initialize this child to a pre-connection state.
*/
apr_pool_clear(ptrans);
if ((ap_max_requests_per_child > 0
&& requests_this_child++ >= ap_max_requests_per_child)) {
clean_child_exit(0);
}
(void) ap_update_child_status(sbh, SERVER_READY, (request_rec *) NULL);
/*
* Wait for an acceptable connection to arrive.
*/
/* Lock around "accept", if necessary */
SAFE_ACCEPT(accept_mutex_on());
if (num_listensocks == 1) {
/* There is only one listener record, so refer to that one. */
lr = ap_listeners;
}
else {
/* multiple listening sockets - need to poll */
for (;;) {
apr_int32_t numdesc;
const apr_pollfd_t *pdesc;
/* timeout == -1 == wait forever */
status = apr_pollset_poll(pollset, -1, &numdesc, &pdesc);
if (status != APR_SUCCESS) {
if (APR_STATUS_IS_EINTR(status)) {
if (one_process && shutdown_pending) {
return;
}
continue;
}
/* Single Unix documents select as returning errnos
* EBADF, EINTR, and EINVAL... and in none of those
* cases does it make sense to continue. In fact
* on Linux 2.0.x we seem to end up with EFAULT
* occasionally, and we'd loop forever due to it.
*/
ap_log_error(APLOG_MARK, APLOG_ERR, status,
ap_server_conf, "apr_pollset_poll: (listen)");
clean_child_exit(1);
}
/* We can always use pdesc[0], but sockets at position N
* could end up completely starved of attention in a very
* busy server. Therefore, we round-robin across the
* returned set of descriptors. While it is possible that
* the returned set of descriptors might flip around and
* continue to starve some sockets, we happen to know the
* internal pollset implementation retains ordering
* stability of the sockets. Thus, the round-robin should
* ensure that a socket will eventually be serviced.
*/
if (last_poll_idx >= numdesc)
last_poll_idx = 0;
/* Grab a listener record from the client_data of the poll
* descriptor, and advance our saved index to round-robin
* the next fetch.
*
* ### hmm... this descriptor might have POLLERR rather
* ### than POLLIN
*/
lr = pdesc[last_poll_idx++].client_data;
goto got_fd;
}
}
got_fd:
/* if we accept() something we don't want to die, so we have to
* defer the exit
*/
status = lr->accept_func(&csd, lr, ptrans);
SAFE_ACCEPT(accept_mutex_off()); /* unlock after "accept" */
if (status == APR_EGENERAL) {
/* resource shortage or should-not-occur occured */
clean_child_exit(1);
}
else if (status != APR_SUCCESS) {
continue;
}
/*
* We now have a connection, so set it up with the appropriate
* socket options, file descriptors, and read/write buffers.
*/
current_conn = ap_run_create_connection(ptrans, ap_server_conf, csd, my_child_num, sbh, bucket_alloc);
if (current_conn) {
ap_process_connection(current_conn, csd);
ap_lingering_close(current_conn);
}
/* Check the pod and the generation number after processing a
* connection so that we'll go away if a graceful restart occurred
* while we were processing the connection or we are the lucky
* idle server process that gets to die.
*/
if (ap_mpm_pod_check(pod) == APR_SUCCESS) { /* selected as idle? */
die_now = 1;
}
else if (ap_my_generation !=
ap_scoreboard_image->global->running_generation) { /* restart? */
/* yeah, this could be non-graceful restart, in which case the
* parent will kill us soon enough, but why bother checking?
*/
die_now = 1;
}
}
clean_child_exit(0);
}
static int make_child(server_rec *s, int slot)
{
int pid;
if (slot + 1 > ap_max_daemons_limit) {
ap_max_daemons_limit = slot + 1;
}
if (one_process) {
apr_signal(SIGHUP, sig_term);
/* Don't catch AP_SIG_GRACEFUL in ONE_PROCESS mode :) */
apr_signal(SIGINT, sig_term);
#ifdef SIGQUIT
apr_signal(SIGQUIT, SIG_DFL);
#endif
apr_signal(SIGTERM, sig_term);
child_main(slot);
return 0;
}
(void) ap_update_child_status_from_indexes(slot, 0, SERVER_STARTING,
(request_rec *) NULL);
#ifdef _OSD_POSIX
/* BS2000 requires a "special" version of fork() before a setuid() call */
if ((pid = os_fork(unixd_config.user_name)) == -1) {
#elif defined(TPF)
if ((pid = os_fork(s, slot)) == -1) {
#else
if ((pid = fork()) == -1) {
#endif
ap_log_error(APLOG_MARK, APLOG_ERR, errno, s, "fork: Unable to fork new process");
/* fork didn't succeed. Fix the scoreboard or else
* it will say SERVER_STARTING forever and ever
*/
(void) ap_update_child_status_from_indexes(slot, 0, SERVER_DEAD,
(request_rec *) NULL);
/* In case system resources are maxxed out, we don't want
* Apache running away with the CPU trying to fork over and
* over and over again.
*/
sleep(10);
return -1;
}
if (!pid) {
#ifdef HAVE_BINDPROCESSOR
/* by default AIX binds to a single processor
* this bit unbinds children which will then bind to another cpu
*/
int status = bindprocessor(BINDPROCESS, (int)getpid(),
PROCESSOR_CLASS_ANY);
if (status != OK) {
ap_log_error(APLOG_MARK, APLOG_WARNING, errno,
ap_server_conf, "processor unbind failed %d", status);
}
#endif
RAISE_SIGSTOP(MAKE_CHILD);
AP_MONCONTROL(1);
/* Disable the parent's signal handlers and set up proper handling in
* the child.
*/
apr_signal(SIGHUP, just_die);
apr_signal(SIGTERM, just_die);
/* The child process doesn't do anything for AP_SIG_GRACEFUL.
* Instead, the pod is used for signalling graceful restart.
*/
apr_signal(AP_SIG_GRACEFUL, SIG_IGN);
child_main(slot);
}
ap_scoreboard_image->parent[slot].pid = pid;
return 0;
}
/* start up a bunch of children */
static void startup_children(int number_to_start)
{
int i;
for (i = 0; number_to_start && i < ap_daemons_limit; ++i) {
if (ap_scoreboard_image->servers[i][0].status != SERVER_DEAD) {
continue;
}
if (make_child(ap_server_conf, i) < 0) {
break;
}
--number_to_start;
}
}
/*
* idle_spawn_rate is the number of children that will be spawned on the
* next maintenance cycle if there aren't enough idle servers. It is
* doubled up to MAX_SPAWN_RATE, and reset only when a cycle goes by
* without the need to spawn.
*/
static int idle_spawn_rate = 1;
#ifndef MAX_SPAWN_RATE
#define MAX_SPAWN_RATE (32)
#endif
static int hold_off_on_exponential_spawning;
static void perform_idle_server_maintenance(apr_pool_t *p)
{
int i;
int to_kill;
int idle_count;
worker_score *ws;
int free_length;
int free_slots[MAX_SPAWN_RATE];
int last_non_dead;
int total_non_dead;
/* initialize the free_list */
free_length = 0;
to_kill = -1;
idle_count = 0;
last_non_dead = -1;
total_non_dead = 0;
for (i = 0; i < ap_daemons_limit; ++i) {
int status;
if (i >= ap_max_daemons_limit && free_length == idle_spawn_rate)
break;
ws = &ap_scoreboard_image->servers[i][0];
status = ws->status;
if (status == SERVER_DEAD) {
/* try to keep children numbers as low as possible */
if (free_length < idle_spawn_rate) {
free_slots[free_length] = i;
++free_length;
}
}
else {
/* We consider a starting server as idle because we started it
* at least a cycle ago, and if it still hasn't finished starting
* then we're just going to swamp things worse by forking more.
* So we hopefully won't need to fork more if we count it.
* This depends on the ordering of SERVER_READY and SERVER_STARTING.
*/
if (status <= SERVER_READY) {
++ idle_count;
/* always kill the highest numbered child if we have to...
* no really well thought out reason ... other than observing
* the server behaviour under linux where lower numbered children
* tend to service more hits (and hence are more likely to have
* their data in cpu caches).
*/
to_kill = i;
}
++total_non_dead;
last_non_dead = i;
}
}
ap_max_daemons_limit = last_non_dead + 1;
if (idle_count > ap_daemons_max_free) {
/* kill off one child... we use the pod because that'll cause it to
* shut down gracefully, in case it happened to pick up a request
* while we were counting
*/
ap_mpm_pod_signal(pod);
idle_spawn_rate = 1;
}
else if (idle_count < ap_daemons_min_free) {
/* terminate the free list */
if (free_length == 0) {
/* only report this condition once */
static int reported = 0;
if (!reported) {
ap_log_error(APLOG_MARK, APLOG_ERR, 0, ap_server_conf,
"server reached MaxClients setting, consider"
" raising the MaxClients setting");
reported = 1;
}
idle_spawn_rate = 1;
}
else {
if (idle_spawn_rate >= 8) {
ap_log_error(APLOG_MARK, APLOG_INFO, 0, ap_server_conf,
"server seems busy, (you may need "
"to increase StartServers, or Min/MaxSpareServers), "
"spawning %d children, there are %d idle, and "
"%d total children", idle_spawn_rate,
idle_count, total_non_dead);
}
for (i = 0; i < free_length; ++i) {
#ifdef TPF
if (make_child(ap_server_conf, free_slots[i]) == -1) {
if(free_length == 1) {
shutdown_pending = 1;
ap_log_error(APLOG_MARK, APLOG_EMERG, 0, ap_server_conf,
"No active child processes: shutting down");
}
}
#else
make_child(ap_server_conf, free_slots[i]);
#endif /* TPF */
}
/* the next time around we want to spawn twice as many if this
* wasn't good enough, but not if we've just done a graceful
*/
if (hold_off_on_exponential_spawning) {
--hold_off_on_exponential_spawning;
}
else if (idle_spawn_rate < MAX_SPAWN_RATE) {
idle_spawn_rate *= 2;
}
}
}
else {
idle_spawn_rate = 1;
}
}
/*****************************************************************
* Executive routines.
*/
int ap_mpm_run(apr_pool_t *_pconf, apr_pool_t *plog, server_rec *s)
{
int index;
int remaining_children_to_start;
apr_status_t rv;
ap_log_pid(pconf, ap_pid_fname);
first_server_limit = server_limit;
if (changed_limit_at_restart) {
ap_log_error(APLOG_MARK, APLOG_WARNING, 0, s,
"WARNING: Attempt to change ServerLimit "
"ignored during restart");
changed_limit_at_restart = 0;
}
/* Initialize cross-process accept lock */
ap_lock_fname = apr_psprintf(_pconf, "%s.%" APR_PID_T_FMT,
ap_server_root_relative(_pconf, ap_lock_fname),
ap_my_pid);
rv = apr_proc_mutex_create(&accept_mutex, ap_lock_fname,
ap_accept_lock_mech, _pconf);
if (rv != APR_SUCCESS) {
ap_log_error(APLOG_MARK, APLOG_EMERG, rv, s,
"Couldn't create accept lock (%s) (%d)",
ap_lock_fname, ap_accept_lock_mech);
mpm_state = AP_MPMQ_STOPPING;
return 1;
}
#if APR_USE_SYSVSEM_SERIALIZE
if (ap_accept_lock_mech == APR_LOCK_DEFAULT ||
ap_accept_lock_mech == APR_LOCK_SYSVSEM) {
#else
if (ap_accept_lock_mech == APR_LOCK_SYSVSEM) {
#endif
rv = unixd_set_proc_mutex_perms(accept_mutex);
if (rv != APR_SUCCESS) {
ap_log_error(APLOG_MARK, APLOG_EMERG, rv, s,
"Couldn't set permissions on cross-process lock; "
"check User and Group directives");
mpm_state = AP_MPMQ_STOPPING;
return 1;
}
}
if (!is_graceful) {
if (ap_run_pre_mpm(s->process->pool, SB_SHARED) != OK) {
mpm_state = AP_MPMQ_STOPPING;
return 1;
}
/* fix the generation number in the global score; we just got a new,
* cleared scoreboard
*/
ap_scoreboard_image->global->running_generation = ap_my_generation;
}
set_signals();
if (one_process) {
AP_MONCONTROL(1);
make_child(ap_server_conf, 0);
}
else {
if (ap_daemons_max_free < ap_daemons_min_free + 1) /* Don't thrash... */
ap_daemons_max_free = ap_daemons_min_free + 1;
/* If we're doing a graceful_restart then we're going to see a lot
* of children exiting immediately when we get into the main loop
* below (because we just sent them AP_SIG_GRACEFUL). This happens pretty
* rapidly... and for each one that exits we'll start a new one until
* we reach at least daemons_min_free. But we may be permitted to
* start more than that, so we'll just keep track of how many we're
* supposed to start up without the 1 second penalty between each fork.
*/
remaining_children_to_start = ap_daemons_to_start;
if (remaining_children_to_start > ap_daemons_limit) {
remaining_children_to_start = ap_daemons_limit;
}
if (!is_graceful) {
startup_children(remaining_children_to_start);
remaining_children_to_start = 0;
}
else {
/* give the system some time to recover before kicking into
* exponential mode
*/
hold_off_on_exponential_spawning = 10;
}
ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, ap_server_conf,
"%s configured -- resuming normal operations",
ap_get_server_version());
ap_log_error(APLOG_MARK, APLOG_INFO, 0, ap_server_conf,
"Server built: %s", ap_get_server_built());
#ifdef AP_MPM_WANT_SET_ACCEPT_LOCK_MECH
ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, ap_server_conf,
"AcceptMutex: %s (default: %s)",
apr_proc_mutex_name(accept_mutex),
apr_proc_mutex_defname());
#endif
restart_pending = shutdown_pending = 0;
mpm_state = AP_MPMQ_RUNNING;
while (!restart_pending && !shutdown_pending) {
int child_slot;
apr_exit_why_e exitwhy;
int status, processed_status;
/* this is a memory leak, but I'll fix it later. */
apr_proc_t pid;
ap_wait_or_timeout(&exitwhy, &status, &pid, pconf);
/* XXX: if it takes longer than 1 second for all our children
* to start up and get into IDLE state then we may spawn an
* extra child
*/
if (pid.pid != -1) {
processed_status = ap_process_child_status(&pid, exitwhy, status);
if (processed_status == APEXIT_CHILDFATAL) {
mpm_state = AP_MPMQ_STOPPING;
return 1;
}
/* non-fatal death... note that it's gone in the scoreboard. */
child_slot = find_child_by_pid(&pid);
if (child_slot >= 0) {
(void) ap_update_child_status_from_indexes(child_slot, 0, SERVER_DEAD,
(request_rec *) NULL);
if (processed_status == APEXIT_CHILDSICK) {
/* child detected a resource shortage (E[NM]FILE, ENOBUFS, etc)
* cut the fork rate to the minimum
*/
idle_spawn_rate = 1;
}
else if (remaining_children_to_start
&& child_slot < ap_daemons_limit) {
/* we're still doing a 1-for-1 replacement of dead
* children with new children
*/
make_child(ap_server_conf, child_slot);
--remaining_children_to_start;
}
#if APR_HAS_OTHER_CHILD
}
else if (apr_proc_other_child_alert(&pid, APR_OC_REASON_DEATH, status) == APR_SUCCESS) {
/* handled */
#endif
}
else if (is_graceful) {
/* Great, we've probably just lost a slot in the
* scoreboard. Somehow we don't know about this
* child.
*/
ap_log_error(APLOG_MARK, APLOG_WARNING,
0, ap_server_conf,
"long lost child came home! (pid %ld)", (long)pid.pid);
}
/* Don't perform idle maintenance when a child dies,
* only do it when there's a timeout. Remember only a
* finite number of children can die, and it's pretty
* pathological for a lot to die suddenly.
*/
continue;
}
else if (remaining_children_to_start) {
/* we hit a 1 second timeout in which none of the previous
* generation of children needed to be reaped... so assume
* they're all done, and pick up the slack if any is left.
*/
startup_children(remaining_children_to_start);
remaining_children_to_start = 0;
/* In any event we really shouldn't do the code below because
* few of the servers we just started are in the IDLE state
* yet, so we'd mistakenly create an extra server.
*/
continue;
}
perform_idle_server_maintenance(pconf);
#ifdef TPF
shutdown_pending = os_check_server(tpf_server_name);
ap_check_signals();
sleep(1);
#endif /*TPF */
}
} /* one_process */
mpm_state = AP_MPMQ_STOPPING;
if (shutdown_pending) {
/* Time to gracefully shut down:
* Kill child processes, tell them to call child_exit, etc...
*/
if (unixd_killpg(getpgrp(), SIGTERM) < 0) {
ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, "killpg SIGTERM");
}
ap_reclaim_child_processes(1); /* Start with SIGTERM */
/* cleanup pid file on normal shutdown */
{
const char *pidfile = NULL;
pidfile = ap_server_root_relative (pconf, ap_pid_fname);
if ( pidfile != NULL && unlink(pidfile) == 0)
ap_log_error(APLOG_MARK, APLOG_INFO,
0, ap_server_conf,
"removed PID file %s (pid=%ld)",
pidfile, (long)getpid());
}
ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, ap_server_conf,
"caught SIGTERM, shutting down");
return 1;
}
/* we've been told to restart */
apr_signal(SIGHUP, SIG_IGN);
if (one_process) {
/* not worth thinking about */
return 1;
}
/* advance to the next generation */
/* XXX: we really need to make sure this new generation number isn't in
* use by any of the children.
*/
++ap_my_generation;
ap_scoreboard_image->global->running_generation = ap_my_generation;
if (is_graceful) {
ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, ap_server_conf,
"Graceful restart requested, doing restart");
/* kill off the idle ones */
ap_mpm_pod_killpg(pod, ap_max_daemons_limit);
/* This is mostly for debugging... so that we know what is still
* gracefully dealing with existing request. This will break
* in a very nasty way if we ever have the scoreboard totally
* file-based (no shared memory)
*/
for (index = 0; index < ap_daemons_limit; ++index) {
if (ap_scoreboard_image->servers[index][0].status != SERVER_DEAD) {
ap_scoreboard_image->servers[index][0].status = SERVER_GRACEFUL;
}
}
}
else {
/* Kill 'em off */
if (unixd_killpg(getpgrp(), SIGHUP) < 0) {
ap_log_error(APLOG_MARK, APLOG_WARNING, errno, ap_server_conf, "killpg SIGHUP");
}
ap_reclaim_child_processes(0); /* Not when just starting up */
ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, ap_server_conf,
"SIGHUP received. Attempting to restart");
}
return 0;
}
/* This really should be a post_config hook, but the error log is already
* redirected by that point, so we need to do this in the open_logs phase.
*/
static int prefork_open_logs(apr_pool_t *p, apr_pool_t *plog, apr_pool_t *ptemp, server_rec *s)
{
apr_status_t rv;
pconf = p;
ap_server_conf = s;
if ((num_listensocks = ap_setup_listeners(ap_server_conf)) < 1) {
ap_log_error(APLOG_MARK, APLOG_ALERT|APLOG_STARTUP, 0,
NULL, "no listening sockets available, shutting down");
return DONE;
}
if ((rv = ap_mpm_pod_open(pconf, &pod))) {
ap_log_error(APLOG_MARK, APLOG_CRIT|APLOG_STARTUP, rv, NULL,
"Could not open pipe-of-death.");
return DONE;
}
return OK;
}
static int prefork_pre_config(apr_pool_t *p, apr_pool_t *plog, apr_pool_t *ptemp)
{
static int restart_num = 0;
int no_detach, debug, foreground;
apr_status_t rv;
mpm_state = AP_MPMQ_STARTING;
debug = ap_exists_config_define("DEBUG");
if (debug) {
foreground = one_process = 1;
no_detach = 0;
}
else
{
no_detach = ap_exists_config_define("NO_DETACH");
one_process = ap_exists_config_define("ONE_PROCESS");
foreground = ap_exists_config_define("FOREGROUND");
}
/* sigh, want this only the second time around */
if (restart_num++ == 1) {
is_graceful = 0;
if (!one_process && !foreground) {
rv = apr_proc_detach(no_detach ? APR_PROC_DETACH_FOREGROUND
: APR_PROC_DETACH_DAEMONIZE);
if (rv != APR_SUCCESS) {
ap_log_error(APLOG_MARK, APLOG_CRIT, rv, NULL,
"apr_proc_detach failed");
return HTTP_INTERNAL_SERVER_ERROR;
}
}
parent_pid = ap_my_pid = getpid();
}
unixd_pre_config(ptemp);
ap_listen_pre_config();
ap_daemons_to_start = DEFAULT_START_DAEMON;
ap_daemons_min_free = DEFAULT_MIN_FREE_DAEMON;
ap_daemons_max_free = DEFAULT_MAX_FREE_DAEMON;
ap_daemons_limit = server_limit;
ap_pid_fname = DEFAULT_PIDLOG;
ap_lock_fname = DEFAULT_LOCKFILE;
ap_max_requests_per_child = DEFAULT_MAX_REQUESTS_PER_CHILD;
ap_extended_status = 0;
#ifdef AP_MPM_WANT_SET_MAX_MEM_FREE
ap_max_mem_free = APR_ALLOCATOR_MAX_FREE_UNLIMITED;
#endif
apr_cpystrn(ap_coredump_dir, ap_server_root, sizeof(ap_coredump_dir));
return OK;
}
static void prefork_hooks(apr_pool_t *p)
{
/* The prefork open_logs phase must run before the core's, or stderr
* will be redirected to a file, and the messages won't print to the
* console.
*/
static const char *const aszSucc[] = {"core.c", NULL};
#ifdef AUX3
(void) set42sig();
#endif
ap_hook_open_logs(prefork_open_logs, NULL, aszSucc, APR_HOOK_MIDDLE);
/* we need to set the MPM state before other pre-config hooks use MPM query
* to retrieve it, so register as REALLY_FIRST
*/
ap_hook_pre_config(prefork_pre_config, NULL, NULL, APR_HOOK_REALLY_FIRST);
}
static const char *set_daemons_to_start(cmd_parms *cmd, void *dummy, const char *arg)
{
const char *err = ap_check_cmd_context(cmd, GLOBAL_ONLY);
if (err != NULL) {
return err;
}
ap_daemons_to_start = atoi(arg);
return NULL;
}
static const char *set_min_free_servers(cmd_parms *cmd, void *dummy, const char *arg)
{
const char *err = ap_check_cmd_context(cmd, GLOBAL_ONLY);
if (err != NULL) {
return err;
}
ap_daemons_min_free = atoi(arg);
if (ap_daemons_min_free <= 0) {
ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL,
"WARNING: detected MinSpareServers set to non-positive.");
ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL,
"Resetting to 1 to avoid almost certain Apache failure.");
ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL,
"Please read the documentation.");
ap_daemons_min_free = 1;
}
return NULL;
}
static const char *set_max_free_servers(cmd_parms *cmd, void *dummy, const char *arg)
{
const char *err = ap_check_cmd_context(cmd, GLOBAL_ONLY);
if (err != NULL) {
return err;
}
ap_daemons_max_free = atoi(arg);
return NULL;
}
static const char *set_max_clients (cmd_parms *cmd, void *dummy, const char *arg)
{
const char *err = ap_check_cmd_context(cmd, GLOBAL_ONLY);
if (err != NULL) {
return err;
}
ap_daemons_limit = atoi(arg);
if (ap_daemons_limit > server_limit) {
ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL,
"WARNING: MaxClients of %d exceeds ServerLimit value "
"of %d servers,", ap_daemons_limit, server_limit);
ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL,
" lowering MaxClients to %d. To increase, please "
"see the ServerLimit", server_limit);
ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL,
" directive.");
ap_daemons_limit = server_limit;
}
else if (ap_daemons_limit < 1) {
ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL,
"WARNING: Require MaxClients > 0, setting to 1");
ap_daemons_limit = 1;
}
return NULL;
}
static const char *set_server_limit (cmd_parms *cmd, void *dummy, const char *arg)
{
int tmp_server_limit;
const char *err = ap_check_cmd_context(cmd, GLOBAL_ONLY);
if (err != NULL) {
return err;
}
tmp_server_limit = atoi(arg);
/* you cannot change ServerLimit across a restart; ignore
* any such attempts
*/
if (first_server_limit &&
tmp_server_limit != server_limit) {
/* how do we log a message? the error log is a bit bucket at this
* point; we'll just have to set a flag so that ap_mpm_run()
* logs a warning later
*/
changed_limit_at_restart = 1;
return NULL;
}
server_limit = tmp_server_limit;
if (server_limit > MAX_SERVER_LIMIT) {
ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL,
"WARNING: ServerLimit of %d exceeds compile time limit "
"of %d servers,", server_limit, MAX_SERVER_LIMIT);
ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL,
" lowering ServerLimit to %d.", MAX_SERVER_LIMIT);
server_limit = MAX_SERVER_LIMIT;
}
else if (server_limit < 1) {
ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL,
"WARNING: Require ServerLimit > 0, setting to 1");
server_limit = 1;
}
return NULL;
}
static const command_rec prefork_cmds[] = {
UNIX_DAEMON_COMMANDS,
LISTEN_COMMANDS,
AP_INIT_TAKE1("StartServers", set_daemons_to_start, NULL, RSRC_CONF,
"Number of child processes launched at server startup"),
AP_INIT_TAKE1("MinSpareServers", set_min_free_servers, NULL, RSRC_CONF,
"Minimum number of idle children, to handle request spikes"),
AP_INIT_TAKE1("MaxSpareServers", set_max_free_servers, NULL, RSRC_CONF,
"Maximum number of idle children"),
AP_INIT_TAKE1("MaxClients", set_max_clients, NULL, RSRC_CONF,
"Maximum number of children alive at the same time"),
AP_INIT_TAKE1("ServerLimit", set_server_limit, NULL, RSRC_CONF,
"Maximum value of MaxClients for this run of Apache"),
{ NULL }
};
module AP_MODULE_DECLARE_DATA mpm_prefork_module = {
MPM20_MODULE_STUFF,
ap_mpm_rewrite_args, /* hook to run before apache parses args */
NULL, /* create per-directory config structure */
NULL, /* merge per-directory config structures */
NULL, /* create per-server config structure */
NULL, /* merge per-server config structures */
prefork_cmds, /* command apr_table_t */
prefork_hooks, /* register hooks */
};
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