* [PATCH 1/1] qemurunner.py: fix race condition at qemu startup
2019-07-12 7:31 [PATCH 0/1] qemurunner.py: fix race condition at qemu startup Chen Qi
@ 2019-07-12 7:31 ` Chen Qi
0 siblings, 0 replies; 2+ messages in thread
From: Chen Qi @ 2019-07-12 7:31 UTC (permalink / raw)
To: openembedded-core
When handling pid file, qemu would first create the file, stat it,
lock it and then write actually contents to it.
So it's possbile that when reading the pid file, the content is empty.
[YOCTO #13390]
Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
---
meta/lib/oeqa/utils/qemurunner.py | 21 ++++++++++++++-------
1 file changed, 14 insertions(+), 7 deletions(-)
diff --git a/meta/lib/oeqa/utils/qemurunner.py b/meta/lib/oeqa/utils/qemurunner.py
index c16227f..68684ae 100644
--- a/meta/lib/oeqa/utils/qemurunner.py
+++ b/meta/lib/oeqa/utils/qemurunner.py
@@ -425,13 +425,20 @@ class QemuRunner:
if not self.runqemu or self.runqemu.poll() is not None:
return False
if os.path.isfile(self.qemu_pidfile):
- f = open(self.qemu_pidfile, 'r')
- qemu_pid = f.read()
- f.close()
- qemupid = int(qemu_pid)
- if os.path.exists("/proc/" + str(qemupid)):
- self.qemupid = qemupid
- return True
+ # when handling pidfile, qemu creates the file, stat it, lock it and then write to it
+ # so it's possible that the file has been created but the content is empty
+ pidfile_timeout = time.time() + 3
+ while time.time() < pidfile_timeout:
+ with open(self.qemu_pidfile, 'r') as f:
+ qemu_pid = f.read().strip()
+ # file created but not yet written contents
+ if not qemu_pid:
+ time.sleep(0.5)
+ continue
+ else:
+ if os.path.exists("/proc/" + qemu_pid):
+ self.qemupid = int(qemu_pid)
+ return True
return False
def run_serial(self, command, raw=False, timeout=60):
--
1.9.1
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