When using eventlet monkey_patch()'d code, greenthreads can be blocked on connection for several seconds while the database contents are parsed. Eventlet recommends adding a sleep(0) call to cooperatively yield in cpu-bound code. asyncio code has asyncio.sleep(0). This patch adds an API method that defaults to doing nothing, but can be overridden to yield as needed.
Signed-off-by: Terry Wilson <twil...@redhat.com> (cherry picked from commit d28c5ca57650d6866453d0adb9a2e048cda21a86) --- NEWS | 6 ++++++ python/ovs/db/idl.py | 11 +++++++++++ 2 files changed, 17 insertions(+) diff --git a/NEWS b/NEWS index d0f0cc8d8..a8ab1aa8b 100644 --- a/NEWS +++ b/NEWS @@ -1,5 +1,11 @@ v2.15.3 - xx xxx xxxx --------------------- + - The Python Idl class now has a cooperative_yield() method that can be + overridden by an application that uses eventlet / gevent / asyncio with + the desired yield method (e.g. {eventlet,gevent,asyncio}.sleep(0)) to + prevent the application from being blocked for a long time while + processing database updates. + v2.15.2 - 21 Oct 2021 --------------------- diff --git a/python/ovs/db/idl.py b/python/ovs/db/idl.py index 3ca47f96b..7ecaeee6d 100644 --- a/python/ovs/db/idl.py +++ b/python/ovs/db/idl.py @@ -491,6 +491,15 @@ class Idl(object): :type updates: Row """ + def cooperative_yield(self): + """Hook for cooperatively yielding to eventlet/gevent/asyncio/etc. + + When a block of code is going to spend a lot of time cpu-bound without + doing any I/O, it can cause greenthread/coroutine libraries to block. + This call should be added to code where this can happen, but defaults + to doing nothing to avoid overhead where it is not needed. + """ + def __send_cond_change(self, table, cond): monitor_cond_change = {table.name: [{"where": cond}]} old_uuid = str(self.uuid) @@ -656,6 +665,8 @@ class Idl(object): 'is not an object' % (table_name, uuid_string)) + self.cooperative_yield() + if version == OVSDB_UPDATE2: changes = self.__process_update2(table, uuid, row_update) if changes: -- 2.31.1 _______________________________________________ dev mailing list d...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-dev