Fix for BUG#28030: test im_instance_conf fails with an assert.

The problem was a race condition on shutdown -- when IM got shutdown
request while a guarded mysqld is starting. In this case the Guardian
thread tried to stop the mysqld, but might fail if the mysqld hadn't
created pid-file so far. When this happened, the mysqld-monitor thread
didn't stop, so the assert in Thread_registry happened.

The fix is to make several attempts to stop mysqld if it is active.


server-tools/instance-manager/guardian.cc:
  Try to stop mysqld several times if it is still active.
server-tools/instance-manager/instance.cc:
  Make Instance::kill_mysqld() to return operation status.
server-tools/instance-manager/instance.h:
  Make Instance::kill_mysqld() to return operation status.
server-tools/instance-manager/thread_registry.cc:
  Log unregistered thread ids.

1 files changed, 5 insertions, 3 deletions

diff --git a/server-tools/instance-manager/instance.cc b/server-tools/instance-manager/instance.cc
index 80e7e99214b..4a1b658737e 100644
--- a/server-tools/instance-manager/instance.cc
+++ b/server-tools/instance-manager/instance.cc
@@ -771,7 +771,7 @@ bool Instance::stop_mysqld()
     These operations should also be used in Guardian to manage instances.
 */
 
-void Instance::kill_mysqld(int signum)
+bool Instance::kill_mysqld(int signum)
 {
   pid_t mysqld_pid= options.load_pid();
 
@@ -780,7 +780,7 @@ void Instance::kill_mysqld(int signum)
     log_info("Instance '%s': no pid file to send a signal (%d).",
              (const char *) get_name()->str,
              (int) signum);
-    return;
+    return TRUE;
   }
 
   log_info("Instance '%s': sending %d to %d...",
@@ -792,7 +792,7 @@ void Instance::kill_mysqld(int signum)
   {
     log_info("Instance '%s': kill() failed.",
              (const char *) get_name()->str);
-    return;
+    return TRUE;
   }
 
   /* Kill suceeded */
@@ -804,6 +804,8 @@ void Instance::kill_mysqld(int signum)
     /* After sucessful hard kill the pidfile need to be removed */
     options.unlink_pidfile();
   }
+
+  return FALSE;
 }