On Fri, Jan 16, 2009 at 12:10:35PM +0000, Richard W.M. Jones wrote:
On Tue, Jan 13, 2009 at 05:46:08PM +0000, Daniel P. Berrange wrote:
@@ -1948,6 +2000,26 @@ static int qemudRunLoop(struct qemud_ser } }
+ /* If number of active workers exceeds both the min_workers + * threshold and the number of clients, then kill some + * off */ + for (i = 0 ; (i < server->nworkers && + server->nactiveworkers > server->nclients && + server->nactiveworkers > min_workers) ; i++) { + + if (server->workers[i].active && + !server->workers[i].processing) { + server->workers[i].quit = 1; + + virCondBroadcast(&server->job); + virMutexUnlock(&server->lock); + pthread_join(server->workers[i].thread, NULL); + virMutexLock(&server->lock); + server->workers[i].active = 0; + server->nactiveworkers--; + } + } +
Doesn't this cause the main loop to hang -- eg. if we happen to try to kill of a worker which is doing some lengthy operation?
If the worker is currently processing an RPC call, its 'processing' flag will be set, and thus we won't consider it a candidate for killing off.
+struct qemud_worker { + pthread_t thread; + int active :1; + int processing :1; + int quit : 1;
I guess maybe I'm unclear about the meaning of these flags. What's the difference between active & processing?
I'll add comments to this struct before commiting. Their meanings are: active: the thread actually exists processing: the thread is currently processing an RPC call quit: the thread has been asked to quit At startup we malloc enough 'struct qemud_worker' objects to hold the entire 'max_workers' set, but we only start threads for 'min_workers. This is what the 'active' field tracks. The 'processing' flag is there so that when we want to kill off a thread, we won't block waiting for a thread that's currently busy working. And the 'quit' flag is that condition that a thread checks upon waking up from its condition variable sleep to see if it was asked to quit. Regards, Daniel -- |: Red Hat, Engineering, London -o- http://people.redhat.com/berrange/ :| |: http://libvirt.org -o- http://virt-manager.org -o- http://ovirt.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :|