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Remove some contention on the DCB zombie queue spinlock

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A fix for final free beign called when a DCB has not yet had a session created
This commit is contained in:
Mark Riddoch
2013-09-05 22:05:55 +02:00
parent 66e9be814b
commit 0d47aa2d3a
1 changed files with 14 additions and 2 deletions
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16
server/core/dcb.c
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@ -161,6 +161,7 @@ dcb_add_to_zombieslist(DCB *dcb)
if (dcb->state == DCB_STATE_ZOMBIE) if (dcb->state == DCB_STATE_ZOMBIE)
{ {
ss_dassert(zombies != NULL); ss_dassert(zombies != NULL);
spinlock_release(&zombiespin);
return; return;
} }
@ -215,7 +216,7 @@ dcb_add_to_zombieslist(DCB *dcb)
static void static void
dcb_final_free(DCB *dcb) dcb_final_free(DCB *dcb)
{ {
SERVICE *service; SERVICE *service = NULL;
CHK_DCB(dcb); CHK_DCB(dcb);
ss_info_dassert(dcb->state == DCB_STATE_DISCONNECTED, ss_info_dassert(dcb->state == DCB_STATE_DISCONNECTED,
@ -249,7 +250,8 @@ SERVICE *service;
/** /**
* Terminate router session. * Terminate router session.
*/ */
service = dcb->session->service; if (dcb->session)
service = dcb->session->service;
if (service != NULL && if (service != NULL &&
service->router != NULL && service->router != NULL &&
@ -320,6 +322,16 @@ DCB* dcb_list = NULL;
DCB* dcb = NULL; DCB* dcb = NULL;
bool succp = false; bool succp = false;
/*
* Perform a dirty read to see if there is anything in the queue.
* This avoids threads hitting the queue spinlock when the queue
* is empty. This will really help when the only entry is being
* freed, since the queue is updated before the expensive call to
* dcb_final_free.
*/
if (!zombies)
return;
spinlock_acquire(&zombiespin); spinlock_acquire(&zombiespin);
ptr = zombies; ptr = zombies;
lptr = NULL; lptr = NULL;