Fix: join consumer timer thread

[lttng-tools.git] / src / bin / lttng-consumerd / lttng-consumerd.c

diff --git a/src/bin/lttng-consumerd/lttng-consumerd.c b/src/bin/lttng-consumerd/lttng-consumerd.c
index 9fb4747536ad7fb3551217f1f3d6aaa0198caae6..fef03c6f64c44060637934ceb5e873198ed70b80 100644 (file)
--- a/src/bin/lttng-consumerd/lttng-consumerd.c
+++ b/src/bin/lttng-consumerd/lttng-consumerd.c
@@ -56,6 +56,7 @@
 
 static pthread_t channel_thread, data_thread, metadata_thread,
                sessiond_thread, metadata_timer_thread, health_thread;
+static bool metadata_timer_thread_online;
 
 /* to count the number of times the user pressed ctrl+c */
 static int sigintcount = 0;
@@ -506,6 +507,20 @@ int main(int argc, char **argv)
        }
        cmm_smp_mb();   /* Read ready before following operations */
 
+       /*
+        * Create the thread to manage the UST metadata periodic timer and
+        * live timer.
+        */
+       ret = pthread_create(&metadata_timer_thread, NULL,
+                       consumer_timer_thread, (void *) ctx);
+       if (ret) {
+               errno = ret;
+               PERROR("pthread_create");
+               retval = -1;
+               goto exit_metadata_timer_thread;
+       }
+       metadata_timer_thread_online = true;
+
        /* Create thread to manage channels */
        ret = pthread_create(&channel_thread, default_pthread_attr(),
                        consumer_thread_channel_poll,
@@ -549,34 +564,12 @@ int main(int argc, char **argv)
                goto exit_sessiond_thread;
        }
 
-       /*
-        * Create the thread to manage the UST metadata periodic timer and
-        * live timer.
-        */
-       ret = pthread_create(&metadata_timer_thread, default_pthread_attr(),
-                       consumer_timer_thread, (void *) ctx);
-       if (ret) {
-               errno = ret;
-               PERROR("pthread_create");
-               retval = -1;
-               goto exit_metadata_timer_thread;
-       }
-
-       ret = pthread_detach(metadata_timer_thread);
-       if (ret) {
-               errno = ret;
-               PERROR("pthread_detach");
-               retval = -1;
-               goto exit_metadata_timer_detach;
-       }
 
        /*
         * This is where we start awaiting program completion (e.g. through
         * signal that asks threads to teardown.
         */
 
-exit_metadata_timer_detach:
-exit_metadata_timer_thread:
        ret = pthread_join(sessiond_thread, &status);
        if (ret) {
                errno = ret;
@@ -617,6 +610,8 @@ exit_metadata_thread:
        }
 exit_channel_thread:
 
+exit_metadata_timer_thread:
+
        ret = pthread_join(health_thread, &status);
        if (ret) {
                errno = ret;
@@ -629,17 +624,38 @@ exit_health_thread:
 exit_health_pipe:
 
 exit_init_data:
-       tmp_ctx = ctx;
-       ctx = NULL;
-       cmm_barrier();  /* Clear ctx for signal handler. */
        /*
         * Wait for all pending call_rcu work to complete before tearing
         * down data structures. call_rcu worker may be trying to
         * perform lookups in those structures.
         */
        rcu_barrier();
-       lttng_consumer_destroy(tmp_ctx);
        lttng_consumer_cleanup();
+       /*
+        * Tearing down the metadata timer thread in a
+        * non-fully-symmetric fashion compared to its creation in case
+        * lttng_consumer_cleanup() ends up tearing down timers (which
+        * requires the timer thread to be alive).
+        */
+       if (metadata_timer_thread_online) {
+               /*
+                * Ensure the metadata timer thread exits only after all other
+                * threads are gone, because it is required to perform timer
+                * teardown synchronization.
+                */
+               kill(getpid(), LTTNG_CONSUMER_SIG_EXIT);
+               ret = pthread_join(metadata_timer_thread, &status);
+               if (ret) {
+                       errno = ret;
+                       PERROR("pthread_join metadata_timer_thread");
+                       retval = -1;
+               }
+               metadata_timer_thread_online = false;
+       }
+       tmp_ctx = ctx;
+       ctx = NULL;
+       cmm_barrier();  /* Clear ctx for signal handler. */
+       lttng_consumer_destroy(tmp_ctx);
 
        if (health_consumerd) {
                health_app_destroy(health_consumerd);