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Unify SIGHUP handling between normal and walsender backends.

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Because walsender and normal backends share the same main loop it's
problematic to have two different flag variables, set in signal
handlers, indicating a pending configuration reload.  Only certain
walsender commands reach code paths checking for the
variable (START_[LOGICAL_]REPLICATION, CREATE_REPLICATION_SLOT
... LOGICAL, notably not base backups).

This is a bug present since the introduction of walsender, but has
gotten worse in releases since then which allow walsender to do more.

A later patch, not slated for v10, will similarly unify SIGHUP
handling in other types of processes as well.

Author: Petr Jelinek, Andres Freund
Reviewed-By: Michael Paquier
Discussion: https://postgr.es/m/20170423235941.qosiuoyqprq4nu7v@alap3.anarazel.de
Backpatch: 9.2-, bug is present since 9.0
This commit is contained in:
Andres Freund
2017-06-05 18:53:41 -07:00
parent c6c3334364
commit 6e1dd2773e
4 changed files with 27 additions and 38 deletions
Download Patch File Download Diff File Expand all files Collapse all files

29
src/backend/replication/walsender.c
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@@ -182,7 +182,6 @@ static bool streamingDoneReceiving;
static bool WalSndCaughtUp = false;
/* Flags set by signal handlers for later service in main loop */
static volatile sig_atomic_t got_SIGHUP = false;
static volatile sig_atomic_t got_SIGUSR2 = false;
static volatile sig_atomic_t got_STOPPING = false;
@@ -218,7 +217,6 @@ static struct
} LagTracker;
/* Signal handlers */
static void WalSndSigHupHandler(SIGNAL_ARGS);
static void WalSndLastCycleHandler(SIGNAL_ARGS);
/* Prototypes for private functions */
@@ -1201,9 +1199,9 @@ WalSndWriteData(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid,
CHECK_FOR_INTERRUPTS();
/* Process any requests or signals received recently */
if (got_SIGHUP)
if (ConfigReloadPending)
{
got_SIGHUP = false;
ConfigReloadPending = false;
ProcessConfigFile(PGC_SIGHUP);
SyncRepInitConfig();
}
@@ -1309,9 +1307,9 @@ WalSndWaitForWal(XLogRecPtr loc)
CHECK_FOR_INTERRUPTS();
/* Process any requests or signals received recently */
if (got_SIGHUP)
if (ConfigReloadPending)
{
got_SIGHUP = false;
ConfigReloadPending = false;
ProcessConfigFile(PGC_SIGHUP);
SyncRepInitConfig();
}
@@ -2101,9 +2099,9 @@ WalSndLoop(WalSndSendDataCallback send_data)
CHECK_FOR_INTERRUPTS();
/* Process any requests or signals received recently */
if (got_SIGHUP)
if (ConfigReloadPending)
{
got_SIGHUP = false;
ConfigReloadPending = false;
ProcessConfigFile(PGC_SIGHUP);
SyncRepInitConfig();
}
@@ -2908,19 +2906,6 @@ HandleWalSndInitStopping(void)
got_STOPPING = true;
}
/* SIGHUP: set flag to re-read config file at next convenient time */
static void
WalSndSigHupHandler(SIGNAL_ARGS)
{
int save_errno = errno;
got_SIGHUP = true;
SetLatch(MyLatch);
errno = save_errno;
}
/*
* SIGUSR2: set flag to do a last cycle and shut down afterwards. The WAL
* sender should already have been switched to WALSNDSTATE_STOPPING at
@@ -2942,7 +2927,7 @@ void
WalSndSignals(void)
{
/* Set up signal handlers */
pqsignal(SIGHUP, WalSndSigHupHandler); /* set flag to read config
pqsignal(SIGHUP, PostgresSigHupHandler); /* set flag to read config
* file */
pqsignal(SIGINT, SIG_IGN); /* not used */
pqsignal(SIGTERM, die); /* request shutdown */