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Fix signal handling in logical replication workers

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The logical replication worker processes now use the normal die()
handler for SIGTERM and CHECK_FOR_INTERRUPTS() instead of custom code.
One problem before was that the apply worker would not exit promptly
when a subscription was dropped, which could lead to deadlocks.

Author: Petr Jelinek <petr.jelinek@2ndquadrant.com>
Reported-by: Masahiko Sawada <sawada.mshk@gmail.com>
This commit is contained in:
Peter Eisentraut
2017-06-02 14:46:00 -04:00
parent acbd8375e9
commit 9fcf670c2e
6 changed files with 50 additions and 21 deletions
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34
src/backend/replication/logical/worker.c
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@ -72,6 +72,8 @@
#include "storage/proc.h"
#include "storage/procarray.h"
#include "tcop/tcopprot.h"
#include "utils/builtins.h"
#include "utils/catcache.h"
#include "utils/datum.h"
@ -118,6 +120,9 @@ static void store_flush_position(XLogRecPtr remote_lsn);
static void reread_subscription(void);
/* Flags set by signal handlers */
static volatile sig_atomic_t got_SIGHUP = false;
/*
* Should this worker apply changes for given relation.
*
@ -1005,7 +1010,7 @@ LogicalRepApplyLoop(XLogRecPtr last_received)
/* mark as idle, before starting to loop */
pgstat_report_activity(STATE_IDLE, NULL);
while (!got_SIGTERM)
for (;;)
{
pgsocket fd = PGINVALID_SOCKET;
int rc;
@ -1015,6 +1020,8 @@ LogicalRepApplyLoop(XLogRecPtr last_received)
TimestampTz last_recv_timestamp = GetCurrentTimestamp();
bool ping_sent = false;
CHECK_FOR_INTERRUPTS();
MemoryContextSwitchTo(ApplyMessageContext);
len = walrcv_receive(wrconn, &buf, &fd);
@ -1437,6 +1444,19 @@ subscription_change_cb(Datum arg, int cacheid, uint32 hashvalue)
MySubscriptionValid = false;
}
/* SIGHUP: set flag to reload configuration at next convenient time */
static void
logicalrep_worker_sighup(SIGNAL_ARGS)
{
int save_errno = errno;
got_SIGHUP = true;
/* Waken anything waiting on the process latch */
SetLatch(MyLatch);
errno = save_errno;
}
/* Logical Replication Apply worker entry point */
void
@ -1454,7 +1474,7 @@ ApplyWorkerMain(Datum main_arg)
/* Setup signal handling */
pqsignal(SIGHUP, logicalrep_worker_sighup);
pqsignal(SIGTERM, logicalrep_worker_sigterm);
pqsignal(SIGTERM, die);
BackgroundWorkerUnblockSignals();
/* Initialise stats to a sanish value */
@ -1604,6 +1624,14 @@ ApplyWorkerMain(Datum main_arg)
/* Run the main loop. */
LogicalRepApplyLoop(origin_startpos);
/* We should only get here if we received SIGTERM */
proc_exit(0);
}
/*
* Is current process a logical replication worker?
*/
bool
IsLogicalWorker(void)
{
return MyLogicalRepWorker != NULL;
}