From a46e2a6e00ab96a70b6cc4c429200f304606cbed Mon Sep 17 00:00:00 2001 From: Mark Washenberger Date: Fri, 18 Nov 2011 17:18:41 -0500 Subject: [PATCH] Workaround xenstore race conditions Change-Id: I17791a78c2008e1bdc41f4f658200808ee72629c --- .../xenapi/etc/xapi.d/plugins/xenstore.py | 20 ++++++++++++------- 1 file changed, 13 insertions(+), 7 deletions(-) diff --git a/plugins/xenserver/xenapi/etc/xapi.d/plugins/xenstore.py b/plugins/xenserver/xenapi/etc/xapi.d/plugins/xenstore.py index c7501308485e..7e27b4ff72db 100755 --- a/plugins/xenserver/xenapi/etc/xapi.d/plugins/xenstore.py +++ b/plugins/xenserver/xenapi/etc/xapi.d/plugins/xenstore.py @@ -91,12 +91,15 @@ def read_record(self, arg_dict): ret, result = _run_command(cmd) return result.strip() except XenstoreError, e: - if arg_dict.get("ignore_missing_path", False): - if not _record_exists(arg_dict): - return "None" - # Either we shouldn't ignore path errors, or another - # error was hit. Re-raise. - raise + if not arg_dict.get("ignore_missing_path", False): + raise + if not _record_exists(arg_dict): + return "None" + # Just try again in case the agent write won the race against + # the record_exists check. If this fails again, it will likely raise + # an equally meaningful XenstoreError as the one we just caught + ret, result = _run_command(cmd) + return result.strip() @jsonify @@ -128,7 +131,10 @@ def list_records(self, arg_dict): except XenstoreError, e: if not _record_exists(arg_dict): return {} - raise + # Just try again in case the path was created in between + # the "ls" and the existence check. If this fails again, it will + # likely raise an equally meaningful XenstoreError + ret, recs = _run_command(cmd) base_path = arg_dict["path"] paths = _paths_from_ls(recs) ret = {}