[sanlock] 01/01: sanlock: Shrink thread pool when there is no work

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nsoffer pushed a commit to annotated tag shrink-pool-v1
in repository sanlock.

commit 19a937183a92b61e0519f4e6d3d83bc24e718991
Author: Nir Soffer 
AuthorDate: Tue Dec 1 14:52:55 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);