[sanlock] branch master updated: sanlock: Shrink thread pool when there is no work

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teigland pushed a commit to branch master
in repository sanlock.

The following commit(s) were added to refs/heads/master by this push:
     new 0ff9c1a  sanlock: Shrink thread pool when there is no work
0ff9c1a is described below

commit 0ff9c1ab8852bec846822ee2af55ebcb7e5f5967
Author: Nir Soffer 
AuthorDate: Tue Dec 1 15:45:03 2020 +0200

sanlock: Shrink thread pool when there is no work

When the thread pool has no work to do, and we have enough free workers,
    other worker threads will terminate.

Without this change, when using large number of worker threads, the
    thread pool grows to max_worker_threads workers, and never shrink down.
    With this change, the pool quickly shrinks down, but we always have
    enough free worker threads for serving new requests.

Signed-off-by: Nir Soffer 
---
 src/main.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/main.c b/src/main.c
index 63d8cff..622dc8e 100644
--- a/src/main.c
+++ b/src/main.c
@@ -932,6 +932,9 @@ static void *thread_pool_worker(void *data)

while (1) {
    	while (!pool.quit && list_empty(&pool.work_data)) {
+			if (pool.free_workers >= DEFAULT_MIN_WORKER_THREADS)
+				goto out;
+
    		pool.free_workers++;
    		pthread_cond_wait(&pool.cond, &pool.mutex);
    		pool.free_workers--;
@@ -952,6 +955,7 @@ static void *thread_pool_worker(void *data)
    		break;
    }

+out:
    pool.num_workers--;
    if (!pool.num_workers)
    	pthread_cond_signal(&pool.quit_wait);