Commit ddf2d98a authored May 08, 2018 by Stefan Hajnoczi Committed by Jeff Cody May 16, 2018

qemu-iotests: reduce chance of races in 185



Commit 8565c3ab ("qemu-iotests: fix
185") identified a race condition in a sub-test.

Similar issues also affect the other sub-tests.  If disk I/O completes
quickly, it races with the QMP 'quit' command.  This causes spurious
test failures because QMP events are emitted in an unpredictable order.

This test relies on QEMU internals and there is no QMP API for getting
deterministic behavior needed to make this test 100% reliable.  At the
same time, the test is useful and it would be a shame to remove it.

Add sleep 0.5 to reduce the chance of races.  This is not a real fix but
appears to reduce spurious failures in practice.

Cc: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20180508135436.30140-2-stefanha@redhat.com
Reviewed-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Jeff Cody <jcody@redhat.com>

parent c416eece

tests/qemu-iotests/185

+12 −0

Original line number	Diff line number	Diff line
		@@ -118,6 +118,9 @@ _send_qemu_cmd $h \
		'speed': 65536 } }" \
		"return"

		# If we don't sleep here 'quit' command races with disk I/O
		sleep 0.5

		_send_qemu_cmd $h "{ 'execute': 'quit' }" "return"
		wait=1 _cleanup_qemu

		@@ -137,6 +140,9 @@ _send_qemu_cmd $h \
		'speed': 65536 } }" \
		"return"

		# If we don't sleep here 'quit' command races with disk I/O
		sleep 0.5

		_send_qemu_cmd $h "{ 'execute': 'quit' }" "return"
		wait=1 _cleanup_qemu

		@@ -183,6 +189,9 @@ _send_qemu_cmd $h \
		'speed': 65536 } }" \
		"return"

		# If we don't sleep here 'quit' command races with disk I/O
		sleep 0.5

		_send_qemu_cmd $h "{ 'execute': 'quit' }" "return"
		wait=1 _cleanup_qemu

		@@ -201,6 +210,9 @@ _send_qemu_cmd $h \
		'speed': 65536 } }" \
		"return"

		# If we don't sleep here 'quit' command races with disk I/O
		sleep 0.5

		_send_qemu_cmd $h "{ 'execute': 'quit' }" "return"
		wait=1 _cleanup_qemu