mds: there is an assertion when calling Beacon::shutdown()

If you run MDSDaemon::init(), an exception occurs that causes MDSDaemon::suicide()--->Beacon::shutdown()--->sender.join();
this problem occurs because sender is just Default-constructed is in Beacon.h(std::thread sender;), there is no call
to Beacon::init() to construct the sender, so the sender has no "joinable"

Fixes: http://tracker.ceph.com/issues/38822
Signed-off-by: huanwen ren <ren.huanwen@zte.com.cn>
(cherry picked from commit 526bbda6f68873a500c78685a7c39a129d8531e5)

diff --git a/src/mds/Beacon.cc b/src/mds/Beacon.cc
index 97b6f9a134505a2da31f1f1f7b630a5abdca9492..fc86bcec88913f44256c5afc68bd22eefb01fd38 100644 (file)
--- a/src/mds/Beacon.cc
+++ b/src/mds/Beacon.cc
@@ -57,7 +57,8 @@ void Beacon::shutdown()
   if (!finished) {
     finished = true;
     lock.unlock();
-    sender.join();
+    if (sender.joinable())
+      sender.join();
   }
 }