Merge "Make time estimation synchronous"

zuul/lib/times.py

@@ -13,63 +13,28 @@
 # under the License.
 
 import logging
-import threading
-import queue
 
 import cachetools
 
 
 class Times:
-    """Perform asynchronous database queries to estimate build times.
-
-    To avoid allowing the SQL database to become a bottelneck when
-    launching builds, this class performs asynchronous queries against
-    the DB and returns estimated build times.
-
-    This is intended as a temporary hedge against performance
-    regressions during Zuul v4 development and can likely be removed
-    once multiple schedulers are supported and possible tightening of
-    database requirements.
-    """
+    """Obtain estimated build times"""
 
     log = logging.getLogger("zuul.times")
 
     def __init__(self, sql, statsd):
         self.sql = sql
         self.statsd = statsd
-        self.queue = queue.Queue()
         self.cache = cachetools.TTLCache(8192, 3600)
-        self.thread = threading.Thread(target=self.run)
-        self.running = False
 
     def start(self):
-        self.running = True
-        self.thread.start()
+        pass
 
     def stop(self):
-        self.running = False
-        self.queue.put(None)
+        pass
 
     def join(self):
-        return self.thread.join()
-
-    def run(self):
-        while self.running:
-            key = self.queue.get()
-            if key is None:
-                continue
-            try:
-                # Double check that we haven't added this key since it
-                # was requested
-                if key in self.cache:
-                    continue
-                if self.statsd:
-                    with self.statsd.timer('zuul.scheduler.time_query'):
-                        self._getTime(key)
-                else:
-                    self._getTime(key)
-            except Exception:
-                self.log.exception("Error querying DB for build %s", key)
+        pass
 
     def _getTime(self, key):
         tenant, project, branch, job = key
@@ -86,6 +51,8 @@ class Times:
         if times:
             estimate = float(sum(times)) / len(times)
             self.cache.setdefault(key, estimate)
+            return estimate
+        return None
         # Don't cache a zero value, so that new jobs get an estimated
         # time ASAP.
 
@@ -95,5 +62,8 @@ class Times:
         if ret is not None:
             return ret
 
-        self.queue.put(key)
-        return None
+        if self.statsd:
+            with self.statsd.timer('zuul.scheduler.time_query'):
+                return self._getTime(key)
+        else:
+            return self._getTime(key)

zuul/manager/__init__.py

@@ -757,14 +757,6 @@ class PipelineManager(metaclass=ABCMeta):
         else:
             relative_priority = 0
         for job in jobs:
-            # Request an estimated time here in order to give the time
-            # thread an opportunity to perform the SQL query in the
-            # background if necessary.
-            self.sched.times.getEstimatedTime(
-                item.pipeline.tenant.name,
-                item.change.project.name,
-                getattr(item.change, 'branch', None),
-                job.name)
             provider = self._getPausedParentProvider(build_set, job)
             priority = self._calculateNodeRequestPriority(build_set, job)
             tenant_name = build_set.item.pipeline.tenant.name