Merge pull request #1749 from ctiller/just-dont-take-forever

Workaround: Prevent threads sitting in epoll forever

src/core/iomgr/pollset_posix.c

@@ -174,6 +174,8 @@ void grpc_pollset_del_fd(grpc_pollset *pollset, grpc_fd *fd) {
 int grpc_pollset_work(grpc_pollset *pollset, gpr_timespec deadline) {
   /* pollset->mu already held */
   gpr_timespec now = gpr_now();
+  /* FIXME(ctiller): see below */
+  gpr_timespec maximum_deadline = gpr_time_add(now, gpr_time_from_seconds(1));
   int r;
   if (gpr_time_cmp(now, deadline) > 0) {
     return 0;
@@ -184,6 +186,11 @@ int grpc_pollset_work(grpc_pollset *pollset, gpr_timespec deadline) {
   if (grpc_alarm_check(&pollset->mu, now, &deadline)) {
     return 1;
   }
+  /* FIXME(ctiller): we should not clamp deadline, however we have some
+     stuck at shutdown bugs that this resolves */
+  if (gpr_time_cmp(deadline, maximum_deadline) > 0) {
+    deadline = maximum_deadline;
+  }
   gpr_tls_set(&g_current_thread_poller, (gpr_intptr)pollset);
   r = pollset->vtable->maybe_work(pollset, deadline, now, 1);
   gpr_tls_set(&g_current_thread_poller, 0);