From c9ad7bba1e7afaf9ce4970a200ee737f176734a2 Mon Sep 17 00:00:00 2001
From: "Stephen R. van den Berg" <srb@cuci.nl>
Date: Mon, 7 May 2018 20:20:22 +0200
Subject: [PATCH] pgsql: Eliminate rare deadlock on heavy interleaved queries.
---
lib/modules/Sql.pmod/pgsql_util.pmod | 28 ++++++++++++++++++----------
1 file changed, 18 insertions(+), 10 deletions(-)
diff --git a/lib/modules/Sql.pmod/pgsql_util.pmod b/lib/modules/Sql.pmod/pgsql_util.pmod
index 081dacd0fd..49e0d80648 100644
--- a/lib/modules/Sql.pmod/pgsql_util.pmod
+++ b/lib/modules/Sql.pmod/pgsql_util.pmod
@@ -384,6 +384,11 @@ class conxion {
final bufcon|conxsess start(void|int waitforreal) {
Thread.MutexKey lock;
+#ifdef PG_DEBUGRACE
+ if (nostash->current_locking_thread())
+ PD("Nostash locked by %s\n",
+ describe_backtrace(nostash->current_locking_thread()->backtrace()));
+#endif
if (lock = (waitforreal ? nostash->lock : nostash->trylock)(1)) {
int mode;
#ifdef PG_DEBUGRACE
@@ -1304,7 +1309,7 @@ class sql_result {
void|bufcon|conxsess plugbuffer = CHAIN(cs);
int retval = KEEP;
PD("%O Try Closeportal %d\n", _portalname, _state);
- Thread.MutexKey lock = closemux->lock();
+ Thread.MutexKey lock = closemux->lock(2); // When called from _sendexecute(), it is already locked
_fetchlimit = 0; // disables further Executes
switch (_state) {
case PARSING:
@@ -1348,16 +1353,19 @@ class sql_result {
private void replenishrows() {
if (_fetchlimit && sizeof(datarows) <= _fetchlimit >> 1) {
- _fetchlimit = pgsqlsess._fetchlimit;
- if (bytesreceived)
- _fetchlimit =
- min((portalbuffersize >> 1) * index / bytesreceived || 1, _fetchlimit);
Thread.MutexKey lock = closemux->lock();
- if (_fetchlimit && inflight <= (_fetchlimit - 1) >> 1)
- _sendexecute(_fetchlimit);
- else if (!_fetchlimit)
- PD("<%O _fetchlimit %d, inflight %d, skip execute\n",
- _portalname, _fetchlimit, inflight);
+ if (_fetchlimit) {
+ _fetchlimit = pgsqlsess._fetchlimit;
+ if (bytesreceived)
+ _fetchlimit =
+ min((portalbuffersize >> 1) * index / bytesreceived || 1, _fetchlimit);
+ if (_fetchlimit)
+ if (inflight <= (_fetchlimit - 1) >> 1)
+ _sendexecute(_fetchlimit);
+ else
+ PD("<%O _fetchlimit %d, inflight %d, skip execute\n",
+ _portalname, _fetchlimit, inflight);
+ }
}
}
--
GitLab