qtest.py: Wait for the result of qtest commands

[Qemu-devel] [PATCH] qtest.py: Wait for the result of qtest commands

Posted by Alberto Garcia 5 years, 2 months ago

The cmd() method of the QEMUQtestProtocol class sends a qtest command
to QEMU but doesn't wait for the return message ("OK", "FAIL", "ERR").
Because of this, it can return control to the caller before the
command has actually finished.

In cases like clock_step or clock_set this means that cmd() can return
before all the timers triggered by the clock change have been fired.
This can be fixed by making cmd() wait for the output of the qtest
command.

This fixes iotests 093 and 136, which are flaky since commit
8258292e18c39480b64eba9f3551 when the machine is under heavy workload.

Signed-off-by: Alberto Garcia <berto@igalia.com>
---
 scripts/qtest.py | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/scripts/qtest.py b/scripts/qtest.py
index adf1fe3f26..afac3fe900 100644
--- a/scripts/qtest.py
+++ b/scripts/qtest.py
@@ -31,6 +31,7 @@ class QEMUQtestProtocol(object):
         """
         self._address = address
         self._sock = self._get_sock()
+        self._sockfile = None
         if server:
             self._sock.bind(self._address)
             self._sock.listen(1)
@@ -49,6 +50,7 @@ class QEMUQtestProtocol(object):
         @raise socket.error on socket connection errors
         """
         self._sock.connect(self._address)
+        self._sockfile = self._sock.makefile()
 
     def accept(self):
         """
@@ -57,6 +59,7 @@ class QEMUQtestProtocol(object):
         @raise socket.error on socket connection errors
         """
         self._sock, _ = self._sock.accept()
+        self._sockfile = self._sock.makefile()
 
     def cmd(self, qtest_cmd):
         """
@@ -65,9 +68,12 @@ class QEMUQtestProtocol(object):
         @param qtest_cmd: qtest command text to be sent
         """
         self._sock.sendall((qtest_cmd + "\n").encode('utf-8'))
+        resp = self._sockfile.readline()
+        return resp
 
     def close(self):
         self._sock.close()
+        self._sockfile.close()
 
     def settimeout(self, timeout):
         self._sock.settimeout(timeout)
-- 
2.11.0

Re: [Qemu-devel] [Qemu-block] [PATCH] qtest.py: Wait for the result of qtest commands

Posted by Stefan Hajnoczi 5 years, 2 months ago

On Thu, Jan 31, 2019 at 02:38:10PM +0200, Alberto Garcia wrote:
> The cmd() method of the QEMUQtestProtocol class sends a qtest command
> to QEMU but doesn't wait for the return message ("OK", "FAIL", "ERR").
> Because of this, it can return control to the caller before the
> command has actually finished.
> 
> In cases like clock_step or clock_set this means that cmd() can return
> before all the timers triggered by the clock change have been fired.
> This can be fixed by making cmd() wait for the output of the qtest
> command.
> 
> This fixes iotests 093 and 136, which are flaky since commit
> 8258292e18c39480b64eba9f3551 when the machine is under heavy workload.
> 
> Signed-off-by: Alberto Garcia <berto@igalia.com>
> ---
>  scripts/qtest.py | 6 ++++++
>  1 file changed, 6 insertions(+)

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

Re: [Qemu-devel] [Qemu-block] [PATCH] qtest.py: Wait for the result of qtest commands

Posted by Kevin Wolf 5 years, 2 months ago

Am 31.01.2019 um 13:38 hat Alberto Garcia geschrieben:
> The cmd() method of the QEMUQtestProtocol class sends a qtest command
> to QEMU but doesn't wait for the return message ("OK", "FAIL", "ERR").
> Because of this, it can return control to the caller before the
> command has actually finished.
> 
> In cases like clock_step or clock_set this means that cmd() can return
> before all the timers triggered by the clock change have been fired.
> This can be fixed by making cmd() wait for the output of the qtest
> command.
> 
> This fixes iotests 093 and 136, which are flaky since commit
> 8258292e18c39480b64eba9f3551 when the machine is under heavy workload.
> 
> Signed-off-by: Alberto Garcia <berto@igalia.com>

Thanks, applied to the block branch.

Kevin

Re: [Qemu-devel] [PATCH] qtest.py: Wait for the result of qtest commands

Posted by Max Reitz 5 years, 2 months ago

On 31.01.19 13:38, Alberto Garcia wrote:
> The cmd() method of the QEMUQtestProtocol class sends a qtest command
> to QEMU but doesn't wait for the return message ("OK", "FAIL", "ERR").
> Because of this, it can return control to the caller before the
> command has actually finished.
> 
> In cases like clock_step or clock_set this means that cmd() can return
> before all the timers triggered by the clock change have been fired.
> This can be fixed by making cmd() wait for the output of the qtest
> command.
> 
> This fixes iotests 093 and 136, which are flaky since commit
> 8258292e18c39480b64eba9f3551 when the machine is under heavy workload.
> 
> Signed-off-by: Alberto Garcia <berto@igalia.com>
> ---
>  scripts/qtest.py | 6 ++++++
>  1 file changed, 6 insertions(+)

Thanks a lot!

Max