From: Mathieu Desnoyers Date: Fri, 16 Jun 2017 21:23:13 +0000 (-0400) Subject: Fix: join consumer timer thread X-Git-Tag: v2.8.8~14 X-Git-Url: https://git.liburcu.org/?p=lttng-tools.git;a=commitdiff_plain;h=bec11ce9cd8cbf36ad6d58b79d5a37f4d78d9a14 Fix: join consumer timer thread Detaching the timer thread has the unfortunate side-effect of letting the health management data structures be freed by main() while the timer thread may still be using them (if, e.g., main() exits quickly). Overcome this situation by tearing down and joining the timer thread. Signed-off-by: Mathieu Desnoyers Signed-off-by: Jérémie Galarneau --- diff --git a/src/bin/lttng-consumerd/lttng-consumerd.c b/src/bin/lttng-consumerd/lttng-consumerd.c index 48d4eec9e..5cf5f3f02 100644 --- 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; @@ -512,6 +513,20 @@ 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, NULL, consumer_thread_channel_poll, @@ -555,34 +570,11 @@ 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, NULL, - 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; @@ -615,6 +607,8 @@ exit_metadata_thread: } exit_channel_thread: +exit_metadata_timer_thread: + ret = pthread_join(health_thread, &status); if (ret) { errno = ret; @@ -627,17 +621,38 @@ 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); diff --git a/src/common/consumer/consumer-timer.c b/src/common/consumer/consumer-timer.c index 08865029d..ebd8b9b88 100644 --- a/src/common/consumer/consumer-timer.c +++ b/src/common/consumer/consumer-timer.c @@ -61,6 +61,10 @@ static void setmask(sigset_t *mask) if (ret) { PERROR("sigaddset live"); } + ret = sigaddset(mask, LTTNG_CONSUMER_SIG_EXIT); + if (ret) { + PERROR("sigaddset exit"); + } } /* @@ -546,7 +550,8 @@ int consumer_signal_init(void) /* * This thread is the sighandler for signals LTTNG_CONSUMER_SIG_SWITCH, - * LTTNG_CONSUMER_SIG_TEARDOWN and LTTNG_CONSUMER_SIG_LIVE. + * LTTNG_CONSUMER_SIG_TEARDOWN, LTTNG_CONSUMER_SIG_LIVE, and + * LTTNG_CONSUMER_SIG_EXIT. */ void *consumer_timer_thread(void *data) { @@ -589,6 +594,9 @@ void *consumer_timer_thread(void *data) DBG("Signal timer metadata thread teardown"); } else if (signr == LTTNG_CONSUMER_SIG_LIVE) { live_timer(ctx, info.si_signo, &info, NULL); + } else if (signr == LTTNG_CONSUMER_SIG_EXIT) { + assert(consumer_quit); + goto end; } else { ERR("Unexpected signal %d\n", info.si_signo); } @@ -597,10 +605,8 @@ void *consumer_timer_thread(void *data) error_testpoint: /* Only reached in testpoint error */ health_error(); +end: health_unregister(health_consumerd); - rcu_unregister_thread(); - - /* Never return */ return NULL; } diff --git a/src/common/consumer/consumer-timer.h b/src/common/consumer/consumer-timer.h index 22e74574c..a970945c6 100644 --- a/src/common/consumer/consumer-timer.h +++ b/src/common/consumer/consumer-timer.h @@ -27,6 +27,7 @@ #define LTTNG_CONSUMER_SIG_SWITCH SIGRTMIN + 10 #define LTTNG_CONSUMER_SIG_TEARDOWN SIGRTMIN + 11 #define LTTNG_CONSUMER_SIG_LIVE SIGRTMIN + 12 +#define LTTNG_CONSUMER_SIG_EXIT SIGRTMIN + 14 #define CLOCKID CLOCK_MONOTONIC diff --git a/src/common/consumer/consumer.h b/src/common/consumer/consumer.h index 66092d3c5..e1a4b7e9e 100644 --- a/src/common/consumer/consumer.h +++ b/src/common/consumer/consumer.h @@ -593,6 +593,12 @@ struct lttng_consumer_global_data { struct lttng_ht *stream_per_chan_id_ht; }; +/* + * Set to nonzero when the consumer is exiting. Updated by signal + * handler and thread exit, read by threads. + */ +extern volatile int consumer_quit; + /* * Init consumer data structures. */