[PATCH] limit filescanner concurrency based on available file descriptors

gistfile1.diff

From 9036ccc8df149916b395226ca141181eb6554144 Mon Sep 17 00:00:00 2001
From: Kai Elwert <elwertk@googlemail.com>
Date: Tue, 6 Aug 2013 10:21:37 +0200
Subject: [PATCH] limit filescanner concurrency based on available file
 descriptors

---
 src/filescanner.c |   12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/src/filescanner.c b/src/filescanner.c
index cefecbd..615f533 100644
--- a/src/filescanner.c
+++ b/src/filescanner.c
@@ -64,6 +64,7 @@ static dispatch_group_t scanner_grp;
 static dispatch_queue_t deferred_pl_sq;
 static int ino_fd;
 static dispatch_source_t ino_src;
+static dispatch_semaphore_t semaphore;
 
 
 #if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
@@ -702,6 +703,7 @@ process_directory_async(char *path, int flags)
   }
     }
 
+  dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
   dispatch_group_async(scanner_grp, dispatch_get_current_queue(),
 		       ^{
 			 int ret;
@@ -725,6 +727,7 @@ process_directory_async(char *path, int flags)
 
 			 free(my_path);
 			 db_pool_release();
+			 dispatch_semaphore_signal(semaphore);
 		       });
 }
 
@@ -1385,6 +1388,13 @@ filescanner_init(void)
 
       goto source_fail;
     }
+  semaphore = dispatch_semaphore_create(getdtablesize() / 4);
+  if (!semaphore)
+    {
+      DPRINTF(E_FATAL, L_SCAN, "Could not get global dispatch queue\n");
+
+      goto source_fail;
+    }
 
   ino_src = dispatch_source_create(DISPATCH_SOURCE_TYPE_READ, ino_fd, 0, global_q);
   if (!ino_src)
@@ -1457,9 +1467,9 @@ filescanner_deinit(void)
 
   ret = dispatch_group_wait(scanner_grp, DISPATCH_TIME_FOREVER);
   dispatch_release(scanner_grp);
+  dispatch_release(semaphore);
 
   if (ret != 0)
     DPRINTF(E_LOG, L_SCAN, "Error waiting for dispatch group\n");
-
   /* deferred_pl_sq resumed & released after completion of the bulk scan */
 }
-- 
1.7.10.4