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https://issues.apache.org/jira/browse/DISPATCH-2238?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17404469#comment-17404469
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ASF GitHub Bot commented on DISPATCH-2238:
------------------------------------------
kgiusti commented on a change in pull request #1349:
URL: https://github.com/apache/qpid-dispatch/pull/1349#discussion_r695775137
##########
File path: src/router_core/router_core_thread.c
##########
@@ -213,25 +187,48 @@ void *router_core_thread(void *arg)
//
sys_mutex_lock(core->action_lock);
- //
- // Block on the condition variable when there is no action to do
- //
- while (core->running && DEQ_IS_EMPTY(core->action_list)) {
- if (!router_core_process_background_action_LH(core))
- sys_cond_wait(core->action_cond, core->action_lock);
+ for (;;) {
+ if (!DEQ_IS_EMPTY(core->action_list)) {
Review comment:
I originally tried exactly that - it was slightly slower than doing the
check before the move. That lock is so heavily contended that *any* extra
instructions run while holding the lock results in longer acquire times by the
I/O threads.
We should be good with initializing the local prior to entering the loop.
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> Avoid holding the core action lock when waking the core thread
> --------------------------------------------------------------
>
> Key: DISPATCH-2238
> URL: https://issues.apache.org/jira/browse/DISPATCH-2238
> Project: Qpid Dispatch
> Issue Type: Improvement
> Components: Router Node
> Affects Versions: 1.17.0
> Reporter: Ken Giusti
> Assignee: Ken Giusti
> Priority: Minor
> Fix For: 1.18.0
>
>
> Currently when an action is queued for the core to process, the queuing code
> calls pthread_cond_signal() while holding the associated mutex. This can
> cause the core thread to be woken then immediately put sleep while taking the
> mutex.
>
> It is legal to call pthread_cond_signal() without holding the lock. Doing
> this will avoid contention on the associated mutex.
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