From b283bdd47e3bc132c1b8ef0ea59d1c12cb8c0ffb Mon Sep 17 00:00:00 2001 From: Vignesh C Date: Thu, 23 Jul 2020 12:35:45 +0530 Subject: [PATCH] Fix for Parallel worker hangs while handling errors. Worker is not able to receive the signals while processing error flow. Worker hangs in this case because when the worker is started the signals will be masked using sigprocmask. Unblocking of signals is done by calling BackgroundWorkerUnblockSignals in ParallelWorkerMain. Now due to error handling the worker has jumped to setjmp in StartBackgroundWorker function. Here the signals are in blocked state, hence the signal is not received by the worker process. --- src/backend/postmaster/bgworker.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/src/backend/postmaster/bgworker.c b/src/backend/postmaster/bgworker.c index beb5e85..a0af580 100644 --- a/src/backend/postmaster/bgworker.c +++ b/src/backend/postmaster/bgworker.c @@ -747,6 +747,17 @@ StartBackgroundWorker(void) */ if (sigsetjmp(local_sigjmp_buf, 1) != 0) { + /* + * Unblock SIGUSR1 signal, it was blocked when the postmaster forker us. + * In case of parallel workers, leader process will send SIGUSR1 signal + * to the worker process(worker process will be in waiting state as + * there is no space available) to indicate shared memory space is freed + * up. Once the signal is received worker process will start populating + * the error message further. + */ + sigdelset(&BlockSig, SIGUSR1); + PG_SETMASK(&BlockSig); + /* Since not using PG_TRY, must reset error stack by hand */ error_context_stack = NULL; -- 1.8.3.1