From 13675d0e093a96a7e7c0aa8c67029fa5e2ed9a68 Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Fri, 16 Jun 2017 17:23:13 -0400 Subject: [PATCH] Fix: join consumer timer thread MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 --- src/bin/lttng-consumerd/lttng-consumerd.c | 68 ++++++++++++++--------- src/common/consumer/consumer-timer.c | 13 +++-- src/common/consumer/consumer-timer.h | 1 + src/common/consumer/consumer.h | 6 ++ 4 files changed, 58 insertions(+), 30 deletions(-) diff --git a/src/bin/lttng-consumerd/lttng-consumerd.c b/src/bin/lttng-consumerd/lttng-consumerd.c index 9fb474753..fef03c6f6 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; @@ -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); diff --git a/src/common/consumer/consumer-timer.c b/src/common/consumer/consumer-timer.c index 0adc5724e..e42940ed9 100644 --- a/src/common/consumer/consumer-timer.c +++ b/src/common/consumer/consumer-timer.c @@ -72,6 +72,10 @@ static void setmask(sigset_t *mask) if (ret) { PERROR("sigaddset monitor"); } + ret = sigaddset(mask, LTTNG_CONSUMER_SIG_EXIT); + if (ret) { + PERROR("sigaddset exit"); + } } static int channel_monitor_pipe = -1; @@ -782,7 +786,7 @@ end: /* * This thread is the sighandler for signals LTTNG_CONSUMER_SIG_SWITCH, * LTTNG_CONSUMER_SIG_TEARDOWN, LTTNG_CONSUMER_SIG_LIVE, and - * LTTNG_CONSUMER_SIG_MONITOR. + * LTTNG_CONSUMER_SIG_MONITOR, LTTNG_CONSUMER_SIG_EXIT. */ void *consumer_timer_thread(void *data) { @@ -836,6 +840,9 @@ void *consumer_timer_thread(void *data) channel = info.si_value.sival_ptr; monitor_timer(ctx, channel); + } else if (signr == LTTNG_CONSUMER_SIG_EXIT) { + assert(CMM_LOAD_SHARED(consumer_quit)); + goto end; } else { ERR("Unexpected signal %d\n", info.si_signo); } @@ -844,10 +851,8 @@ 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 851a172aa..1b5dd414c 100644 --- a/src/common/consumer/consumer-timer.h +++ b/src/common/consumer/consumer-timer.h @@ -28,6 +28,7 @@ #define LTTNG_CONSUMER_SIG_TEARDOWN SIGRTMIN + 11 #define LTTNG_CONSUMER_SIG_LIVE SIGRTMIN + 12 #define LTTNG_CONSUMER_SIG_MONITOR SIGRTMIN + 13 +#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 220dbb4a2..3111471db 100644 --- a/src/common/consumer/consumer.h +++ b/src/common/consumer/consumer.h @@ -610,6 +610,12 @@ struct lttng_consumer_global_data { */ extern int consumer_quit; +/* + * Set to nonzero when the consumer is exiting. Updated by signal + * handler and thread exit, read by threads. + */ +extern int consumer_quit; + /* Flag used to temporarily pause data consumption from testpoints. */ extern int data_consumption_paused; -- 2.34.1