Fix debugger deadlock.
Fixes a deadlock between the event thread lock and the processing request
lock where the JDWP thread and the event thread wait for each other. We now
move the call to StartProcessingRequest after the call to SetWaitForEventThread
in JdwpState::ProcessRequest so locks are taken in the same order in both
threads.
Also adds some thread safety annotations and JDWP verbose logs for debug (only
enabled if we pass the -verbose:jdwp option to the runtime).
Bug: 13165103
Change-Id: I4e8b6526d973bfee56e69e8e14eddf56adfa1939
diff --git a/runtime/jdwp/jdwp_handler.cc b/runtime/jdwp/jdwp_handler.cc
index 0ff78d0..4b170ba 100644
--- a/runtime/jdwp/jdwp_handler.cc
+++ b/runtime/jdwp/jdwp_handler.cc
@@ -1685,6 +1685,12 @@
SetWaitForEventThread(0);
/*
+ * We do not want events to be sent while we process a request. Indicate the JDWP thread starts
+ * to process a request so other threads wait for it to finish before sending an event.
+ */
+ StartProcessingRequest();
+
+ /*
* Tell the VM that we're running and shouldn't be interrupted by GC.
* Do this after anything that can stall indefinitely.
*/
@@ -1779,9 +1785,15 @@
Thread* self = Thread::Current();
CHECK_NE(self, GetDebugThread()) << "Events should not be posted by debug thread";
MutexLock mu(self, process_request_lock_);
+ bool waited = false;
while (processing_request_) {
+ VLOG(jdwp) << StringPrintf("wait for processing request");
+ waited = true;
process_request_cond_.Wait(self);
}
+ if (waited) {
+ VLOG(jdwp) << StringPrintf("finished waiting for processing request");
+ }
CHECK_EQ(processing_request_, false);
}