racing in chip_im_initiator, exchange context leak

[kghost]

Problem

Cirque fail: https://github.com/project-chip/connectedhomeip/actions/runs/844261919

There is a racing in chip_im_initiator tests. sometime ExchangeContext is leaked

chip-im-initiator: ../../../../../src/messaging/ExchangeMgr.cpp:101: chip::Messaging::ExchangeManager::Shutdown()::<lambda(auto:2*)> [with auto:2 = chip::Messaging::ExchangeContext]: Assertion `false' failed.

Apply following patch will make it fail everytime.

diff --git a/src/app/tests/integration/chip_im_initiator.cpp b/src/app/tests/integration/chip_im_initiator.cpp
index 09bceacc..9e971132 100644
--- a/src/app/tests/integration/chip_im_initiator.cpp
+++ b/src/app/tests/integration/chip_im_initiator.cpp
@@ -191,6 +191,7 @@ void HandleReadComplete()
            static_cast<double>(gReadRespCount) * 100 / gReadCount, static_cast<double>(transitTime) / 1000);
 
     gCond.notify_one();
+    usleep(20);
 }
 
 class MockInteractionModelApp : public chip::app::InteractionModelDelegate

There are 2 threads:

Event thread (Thread E):

1. send read request
2. receive read response
3. notify main thread read successful
4. delete ExchangeContext

Main thread (Thread M):

1. Wait for read successful
2. Shutdown ExchangeManager

if Shutting down the ExchangeManager happens before deleting the ExchangeContext, there will be an assert fail

Proposed Solution

Lock guard ExchangeManager::Shutdown

[woody-apple]

Is this still an issue?