sin/samba-mirror
1
0
Fork 0
mirror of https://github.com/samba-team/samba.git synced 2025-03-22 02:50:28 +03:00
Code

s3: Avoid a thundering herd in g_lock_unlock

Browse Source 
Only notify the first 5 pending lock waiters. This avoids a thundering herd
problem that is really nasty in a cluster. It also makes acquiring a lock a bit
more FIFO, lock waiters are added to the end of the array.
This commit is contained in:
Volker Lendecke 2010-02-16 12:22:08 +01:00
parent 07978bd175
commit 725b3654f8
1 changed files with 16 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
source3/lib/g_lock.c
View File

@ -530,13 +530,23 @@ static NTSTATUS g_lock_force_unlock(struct g_lock_ctx *ctx, const char *name,
}
if ((lock_type & G_LOCK_PENDING) == 0) {
int num_wakeups = 0;
/*
* We've been the lock holder. Tell all others to retry.
* We've been the lock holder. Others to retry. Don't
* tell all others to avoid a thundering herd. In case
* this leads to a complete stall because we miss some
* processes, the loop in g_lock_lock tries at least
* once a minute.
*/
for (i=0; i<num_locks; i++) {
if ((locks[i].lock_type & G_LOCK_PENDING) == 0) {
continue;
}
if (!process_exists(locks[i].pid)) {
continue;
}
/*
* Ping all waiters to retry
@ -549,6 +559,11 @@ static NTSTATUS g_lock_force_unlock(struct g_lock_ctx *ctx, const char *name,
procid_str(talloc_tos(),
&locks[i].pid),
nt_errstr(status)));
} else {
num_wakeups += 1;
}
if (num_wakeups > 5) {
break;
}
}
}