diff options
Diffstat (limited to 'src/backend/access/transam/parallel.c')
| -rw-r--r-- | src/backend/access/transam/parallel.c | 19 |
1 files changed, 16 insertions, 3 deletions
diff --git a/src/backend/access/transam/parallel.c b/src/backend/access/transam/parallel.c index 4a2e352d579..a10bf02ccff 100644 --- a/src/backend/access/transam/parallel.c +++ b/src/backend/access/transam/parallel.c @@ -231,6 +231,15 @@ InitializeParallelDSM(ParallelContext *pcxt) shm_toc_estimate_keys(&pcxt->estimator, 1); /* + * If we manage to reach here while non-interruptible, it's unsafe to + * launch any workers: we would fail to process interrupts sent by them. + * We can deal with that edge case by pretending no workers were + * requested. + */ + if (!INTERRUPTS_CAN_BE_PROCESSED()) + pcxt->nworkers = 0; + + /* * Normally, the user will have requested at least one worker process, but * if by chance they have not, we can skip a bunch of things here. */ @@ -476,6 +485,9 @@ InitializeParallelDSM(ParallelContext *pcxt) shm_toc_insert(pcxt->toc, PARALLEL_KEY_ENTRYPOINT, entrypointstate); } + /* Update nworkers_to_launch, in case we changed nworkers above. */ + pcxt->nworkers_to_launch = pcxt->nworkers; + /* Restore previous memory context. */ MemoryContextSwitchTo(oldcontext); } @@ -539,10 +551,11 @@ ReinitializeParallelWorkers(ParallelContext *pcxt, int nworkers_to_launch) { /* * The number of workers that need to be launched must be less than the - * number of workers with which the parallel context is initialized. + * number of workers with which the parallel context is initialized. But + * the caller might not know that InitializeParallelDSM reduced nworkers, + * so just silently trim the request. */ - Assert(pcxt->nworkers >= nworkers_to_launch); - pcxt->nworkers_to_launch = nworkers_to_launch; + pcxt->nworkers_to_launch = Min(pcxt->nworkers, nworkers_to_launch); } /* |