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Blocked clients can stall when under low load

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Former-commit-id: 7468c691ad04829c1fd3ae69f206946e8f38254a
This commit is contained in:
John Sully 2019-07-13 16:44:11 -04:00
parent 0f5b59241f
commit b82cf7f034
2 changed files with 21 additions and 0 deletions
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3
src/blocked.cpp
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@ -64,6 +64,7 @@
*/
#include "server.h"
#include <mutex>
int serveClientBlockedOnList(client *receiver, robj *key, robj *dstkey, redisDb *db, robj *value, int where);
@ -180,6 +181,7 @@ void queueClientForReprocessing(client *c) {
* of operation the client is blocking for. */
void unblockClient(client *c) {
serverAssert(GlobalLocksAcquired());
serverAssert(c->lock.fOwnLock());
if (c->btype == BLOCKED_LIST ||
c->btype == BLOCKED_ZSET ||
c->btype == BLOCKED_STREAM) {
@ -301,6 +303,7 @@ void handleClientsBlockedOnKeys(void) {
while(numclients--) {
listNode *clientnode = listFirst(clients);
client *receiver = (client*)clientnode->value;
std::unique_lock<decltype(client::lock)> lock(receiver->lock);
if (receiver->btype != BLOCKED_LIST) {
/* Put at the tail, so that at the next call

18
src/server.cpp
View File

@ -1785,6 +1785,15 @@ int serverCron(struct aeEventLoop *eventLoop, long long id, void *clientData) {
UNUSED(id);
UNUSED(clientData);
/* If another threads unblocked one of our clients, and this thread has been idle
then beforeSleep won't have a chance to process the unblocking. So we also
process them here in the cron job to ensure they don't starve.
*/
if (listLength(g_pserver->rgthreadvar[IDX_EVENT_LOOP_MAIN].unblocked_clients))
{
processUnblockedClients(IDX_EVENT_LOOP_MAIN);
}
ProcessPendingAsyncWrites(); // This is really a bug, but for now catch any laggards that didn't clean up
/* Software watchdog: deliver the SIGALRM that will reach the signal
@ -2051,6 +2060,15 @@ int serverCronLite(struct aeEventLoop *eventLoop, long long id, void *clientData
int iel = ielFromEventLoop(eventLoop);
serverAssert(iel != IDX_EVENT_LOOP_MAIN);
/* If another threads unblocked one of our clients, and this thread has been idle
then beforeSleep won't have a chance to process the unblocking. So we also
process them here in the cron job to ensure they don't starve.
*/
if (listLength(g_pserver->rgthreadvar[iel].unblocked_clients))
{
processUnblockedClients(iel);
}
ProcessPendingAsyncWrites(); // A bug but leave for now, events should clean up after themselves
clientsCron(iel);