fix: Fix deadlock on mutex protecting thread_ids.

dasch-swiss · Jan 24, 2017 · f42d3e3 · f42d3e3
1 parent c94b392
commit f42d3e3
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Showing 2 changed files with 12 additions and 9 deletions.
diff --git a/shttps/Server.cpp b/shttps/Server.cpp
@@ -1065,25 +1065,28 @@ namespace shttps {
         old_ll = setlogmask(LOG_MASK(LOG_INFO));
         syslog(LOG_INFO, "Server shutting down");
         setlogmask(old_ll);
+        std::vector<pthread_t> threads_to_join;
 
         {
             std::lock_guard<std::mutex> thread_mutex_guard(threadlock);
 
             // Send the close message to all running threads.
             for (auto const &tid : thread_ids) {
+                threads_to_join.push_back(tid.first);
                 Server::CommMsg::send(tid.second.commpipe_write);
             }
+        }
 
-            close(stoppipe[0]);
-            close(stoppipe[1]);
+        close(stoppipe[0]);
+        close(stoppipe[1]);
 
-            // We have closed all sockets, now wait for the threads to terminate.
-            for (auto const &tid : thread_ids) {
-                int err;
+        // We have closed all sockets, now wait for the threads to terminate.
 
-                if ((err = pthread_join(tid.first, nullptr)) != 0) {
-                    syslog(LOG_ERR, "pthread_join failed with error code %d", err);
-                }
+        for (auto const &thread_to_join : threads_to_join) {
+            int err = pthread_join(thread_to_join, nullptr);
+
+            if (err != 0) {
+                syslog(LOG_ERR, "pthread_join failed with error code %d", err);
             }
         }
 

diff --git a/shttps/Server.h b/shttps/Server.h
@@ -213,7 +213,7 @@ namespace shttps {
         std::string semname; //!< name of the semaphore for restricting the number of threads
         sem_t *_semaphore; //!< semaphore
         std::atomic<int> _semcnt; //!< current value of semaphore (sem_getvalue() is not available on all systems)
-        std::map<pthread_t,GenericSockId> thread_ids; //!< Map of active worker threads
+        std::map<pthread_t, GenericSockId> thread_ids; //!< Map of active worker threads
         int _keep_alive_timeout;
         bool running; //!< Main runloop should keep on going
         std::map<std::string, RequestHandler> handler[9]; // request handlers for the different 9 request methods