Move extra code out of the Pre/PostRestoreCommand() section.

If SIGTERM is received within this section, the startup process
will immediately proc_exit() in the signal handler, so it is
inadvisable to include any more code than is required there (as
such code is unlikely to be compatible with doing proc_exit() in a
signal handler).  This commit moves the code recently added to this
section (see 1b06d7bac9 and 7fed801135) to outside of the section.
This ensures that the startup process only calls proc_exit() in its
SIGTERM handler for the duration of the system() call, which is how
this code worked from v8.4 to v14.

Reported-by: Michael Paquier, Thomas Munro
Analyzed-by: Andres Freund
Suggested-by: Tom Lane
Reviewed-by: Michael Paquier, Robert Haas, Thomas Munro, Andres Freund
Discussion: https://postgr.es/m/Y9nGDSgIm83FHcad%40paquier.xyz
Discussion: https://postgr.es/m/20230223231503.GA743455%40nathanxps13
Backpatch-through: 15
This commit is contained in:
Nathan Bossart 2023-10-16 12:41:55 -05:00
parent a70bce43fb
commit 8fb13dd6ab
1 changed files with 11 additions and 4 deletions

View File

@ -159,20 +159,27 @@ RestoreArchivedFile(char *path, const char *xlogfname,
(errmsg_internal("executing restore command \"%s\"",
xlogRestoreCmd)));
fflush(NULL);
pgstat_report_wait_start(WAIT_EVENT_RESTORE_COMMAND);
/*
* Check signals before restore command and reset afterwards.
* PreRestoreCommand() informs the SIGTERM handler for the startup process
* that it should proc_exit() right away. This is done for the duration
* of the system() call because there isn't a good way to break out while
* it is executing. Since we might call proc_exit() in a signal handler,
* it is best to put any additional logic before or after the
* PreRestoreCommand()/PostRestoreCommand() section.
*/
PreRestoreCommand();
/*
* Copy xlog from archival storage to XLOGDIR
*/
fflush(NULL);
pgstat_report_wait_start(WAIT_EVENT_RESTORE_COMMAND);
rc = system(xlogRestoreCmd);
pgstat_report_wait_end();
PostRestoreCommand();
pgstat_report_wait_end();
pfree(xlogRestoreCmd);
if (rc == 0)