Minor changes
diff --git a/include/grpc++/server_builder.h b/include/grpc++/server_builder.h
index 68c5344..a56f81d 100644
--- a/include/grpc++/server_builder.h
+++ b/include/grpc++/server_builder.h
@@ -195,7 +195,10 @@
struct SyncServerSettings {
SyncServerSettings()
- : num_cqs(gpr_cpu_num_cores()), min_pollers(1), max_pollers(2), cq_timeout_msec(10000) {}
+ : num_cqs(gpr_cpu_num_cores()),
+ min_pollers(1),
+ max_pollers(2),
+ cq_timeout_msec(10000) {}
// Number of server completion queues to create to listen to incoming RPCs.
int num_cqs;
diff --git a/src/core/lib/iomgr/ev_epoll_linux.c b/src/core/lib/iomgr/ev_epoll_linux.c
index 16a9199..a686d9e 100644
--- a/src/core/lib/iomgr/ev_epoll_linux.c
+++ b/src/core/lib/iomgr/ev_epoll_linux.c
@@ -237,6 +237,7 @@
/* Wakeup fd used to wake pollers to check the contents of workqueue_items */
grpc_wakeup_fd workqueue_wakeup_fd;
+ /* The list of workers waiting to do polling on this polling island */
gpr_mu worker_list_mu;
worker_node worker_list_head;
@@ -265,7 +266,10 @@
struct grpc_pollset_worker *next;
struct grpc_pollset_worker *prev;
+ /* Indicates if it is this worker's turn to do epoll */
gpr_atm is_polling_turn;
+
+ /* Node in the polling island's worker list. */
worker_node pi_list_link;
};
@@ -1468,12 +1472,12 @@
gpr_timespec *now) {
bool is_lease_acquired = false;
- gpr_mu_lock(&pi->worker_list_mu); // Lock
+ gpr_mu_lock(&pi->worker_list_mu); // LOCK
long num_pollers = gpr_atm_no_barrier_load(&pi->poller_count);
if (num_pollers >= GRPC_MAX_POLLERS_PER_ISLAND) {
push_back_worker_node(&pi->worker_list_head, &worker->pi_list_link);
- gpr_mu_unlock(&pi->worker_list_mu); // Unlock
+ gpr_mu_unlock(&pi->worker_list_mu); // UNLOCK
bool is_timeout = false;
int ret;
@@ -1487,51 +1491,54 @@
if (ret == -1) {
if (errno == EAGAIN) {
- // gpr_log(GPR_INFO, "timeout"); // TODO: sreek remove this
- // log-line
+ is_timeout = true;
} else {
+ /* TODO: sreek This should not happen. If we see these log messages, it
+ * means we are most likely something incorrect in the setup needed for
+ * sigwaitinfo/sigtimedwait */
gpr_log(GPR_ERROR, "Failed with retcode: %d (timeout_ms: %d)", errno,
timeout_ms);
}
- is_timeout = true;
}
+ /* Did the worker come out of sigtimedwait due to a thread that just
+ * exited epoll and kicking it (in release_polling_lease function). */
bool is_polling_turn = gpr_atm_acq_load(&worker->is_polling_turn);
- /*
- if (is_polling_turn) {
-/ gpr_log(GPR_ERROR, "do epoll is true (timeout_ms:%d)",
- timeout_ms); // TODO: sreek remove this logline
- }
- */
+ /* Did the worker come out of sigtimedwait due to a thread alerting it that
+ * some completion event was (likely) available in the completion queue */
bool is_kicked = gpr_atm_no_barrier_load(&worker->is_kicked);
+
if (is_kicked || is_timeout) {
- *now = deadline;
+ *now = deadline; /* Essentially make the epoll timeout = 0 */
} else if (is_polling_turn) {
- *now = gpr_now(GPR_CLOCK_MONOTONIC);
+ *now = gpr_now(GPR_CLOCK_MONOTONIC); /* Reduce the epoll timeout */
}
- gpr_mu_lock(&pi->worker_list_mu); // Lock
+ gpr_mu_lock(&pi->worker_list_mu); // LOCK
/* The node might have already been removed from the list by the poller
that kicked this. However it is safe to call 'remove_worker_node' on
an already detached node */
remove_worker_node(&worker->pi_list_link);
+ /* It is important to read the num_pollers again under the lock so that we
+ * have the latest num_pollers value that doesn't change while we are doing
+ * the "(num_pollers < GPRC_MAX_POLLERS_PER_ISLAND)" a a few lines below */
num_pollers = gpr_atm_no_barrier_load(&pi->poller_count);
}
if (num_pollers < GRPC_MAX_POLLERS_PER_ISLAND) {
- gpr_atm_no_barrier_fetch_add(&pi->poller_count, 1); // Add a poller
+ gpr_atm_no_barrier_fetch_add(&pi->poller_count, 1);
is_lease_acquired = true;
}
- gpr_mu_unlock(&pi->worker_list_mu); // Unlock
+ gpr_mu_unlock(&pi->worker_list_mu); // UNLOCK
return is_lease_acquired;
}
static void release_polling_lease(polling_island *pi, grpc_error **error) {
gpr_mu_lock(&pi->worker_list_mu); // Lock
- gpr_atm_no_barrier_fetch_add(&pi->poller_count, -1); // Remove poller
+ gpr_atm_no_barrier_fetch_add(&pi->poller_count, -1);
worker_node *node = pop_front_worker_node(&pi->worker_list_head);
if (node != NULL) {
grpc_pollset_worker *next_worker = WORKER_FROM_WORKER_LIST_NODE(node);