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pg_upgrade: fix -j race condition on Windows

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Pg_Upgrade cannot write the command string to the log file and then call
system() to write to the same file without causing occasional file-share
errors on Windows.  So instead, write the command string to the log file
after system(), in those cases.
Backpatch to 9.3.
This commit is contained in:
Bruce Momjian 2013-07-27 15:00:58 -04:00
parent 61edd52401
commit d83940a7f6
1 changed files with 41 additions and 5 deletions
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46
contrib/pg_upgrade/exec.c
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@ -37,12 +37,14 @@ static int win32_check_directory_write_permissions(void);
* If throw_error is true, this raises a PG_FATAL error and pg_upgrade
* terminates; otherwise it is just reported as PG_REPORT and exec_prog()
* returns false.
*
* The code requires it be called first from the primary thread on Windows.
*/
bool
exec_prog(const char *log_file, const char *opt_log_file,
bool throw_error, const char *fmt,...)
{
int result;
int result = 0;
int written;
#define MAXCMDLEN (2 * MAXPGPATH)
@ -50,6 +52,14 @@ exec_prog(const char *log_file, const char *opt_log_file,
FILE *log;
va_list ap;
#ifdef WIN32
static DWORD mainThreadId = 0;
/* We assume we are called from the primary thread first */
if (mainThreadId == 0)
mainThreadId = GetCurrentThreadId();
#endif
written = strlcpy(cmd, SYSTEMQUOTE, sizeof(cmd));
va_start(ap, fmt);
written += vsnprintf(cmd + written, MAXCMDLEN - written, fmt, ap);
@ -61,6 +71,22 @@ exec_prog(const char *log_file, const char *opt_log_file,
if (written >= MAXCMDLEN)
pg_log(PG_FATAL, "command too long\n");
pg_log(PG_VERBOSE, "%s\n", cmd);
#ifdef WIN32
/*
* For some reason, Windows issues a file-in-use error if we write data
* to the log file from a non-primary thread just before we create a
* subprocess that also writes to the same log file. One fix is to
* sleep for 100ms. A cleaner fix is to write to the log file _after_
* the subprocess has completed, so we do this only when writing from
* a non-primary thread. fflush(), running system() twice, and
* pre-creating the file do not see to help.
*/
if (mainThreadId != GetCurrentThreadId())
result = system(cmd);
#endif
log = fopen(log_file, "a");
#ifdef WIN32
@ -84,11 +110,18 @@ exec_prog(const char *log_file, const char *opt_log_file,
if (log == NULL)
pg_log(PG_FATAL, "cannot write to log file %s\n", log_file);
#ifdef WIN32
fprintf(log, "\n\n");
/* Are we printing "command:" before its output? */
if (mainThreadId == GetCurrentThreadId())
fprintf(log, "\n\n");
#endif
pg_log(PG_VERBOSE, "%s\n", cmd);
fprintf(log, "command: %s\n", cmd);
#ifdef WIN32
/* Are we printing "command:" after its output? */
if (mainThreadId != GetCurrentThreadId())
fprintf(log, "\n\n");
#endif
/*
* In Windows, we must close the log file at this point so the file is not
@ -96,7 +129,11 @@ exec_prog(const char *log_file, const char *opt_log_file,
*/
fclose(log);
result = system(cmd);
#ifdef WIN32
/* see comment above */
if (mainThreadId == GetCurrentThreadId())
#endif
result = system(cmd);
if (result != 0)
{
@ -118,7 +155,6 @@ exec_prog(const char *log_file, const char *opt_log_file,
}
#ifndef WIN32
/*
* We can't do this on Windows because it will keep the "pg_ctl start"
* output filename open until the server stops, so we do the \n\n above on