worker timeout wrapper, and use for kafka

1 files changed, 40 insertions, 2 deletions

diff --git a/python/sandcrawler/workers.py b/python/sandcrawler/workers.py
index d5db7a5..9f1b55c 100644
--- a/python/sandcrawler/workers.py
+++ b/python/sandcrawler/workers.py
@@ -2,6 +2,7 @@
 import sys
 import json
 import time
+import signal
 import zipfile
 import multiprocessing.pool
 from collections import Counter
@@ -40,6 +41,43 @@ class SandcrawlerWorker(object):
             print(json.dumps(result))
         return result
 
+    def timeout_response(self, task):
+        """
+        This should be overridden by workers that want to return something
+        meaningful when there is a processing timeout. Eg, JSON vs some other
+        error message.
+        """
+        return None
+
+    def push_record_timeout(self, task, timeout=300):
+        """
+        A wrapper around self.push_record which sets a timeout.
+
+        Note that this uses signals and *will behave wrong/weirdly* with
+        multithreading or if signal-based timeouts are used elsewhere in the
+        same process.
+        """
+
+        def timeout_handler(signum, frame):
+            raise TimeoutError("timeout processing record")
+        signal.signal(signal.SIGALRM, timeout_handler)
+        resp = None
+        signal.alarm(int(timeout))
+        try:
+            resp = self.push_record(task)
+        except TimeoutError:
+            self.counts['timeout'] += 1
+            resp = self.timeout_response(task) # pylint: disable=assignment-from-none
+            # TODO: what if it is this push_record() itself that is timing out?
+            if self.sink:
+                self.sink.push_record(resp)
+                self.counts['pushed'] += 1
+            else:
+                print(json.dumps(resp))
+        finally:
+            signal.alarm(0)
+        return resp
+
     def push_batch(self, tasks):
         results = []
         for task in tasks:
@@ -338,7 +376,6 @@ class ZipfilePusher(RecordPusher):
         print("ZIP PDFs pushed: {}".format(self.counts), file=sys.stderr)
         return self.counts
 
-
 class KafkaJsonPusher(RecordPusher):
 
     def __init__(self, worker, kafka_hosts, consume_topic, group, **kwargs):
@@ -398,7 +435,8 @@ class KafkaJsonPusher(RecordPusher):
                     done = False
                     while not done:
                         try:
-                            self.worker.push_record(record)
+                            # use timeouts; don't want kafka itself to timeout
+                            self.worker.push_record_timeout(record, timeout=300)
                             break
                         except SandcrawlerBackoffError as be:
                             print("Backing off for 200 seconds: {}".format(be))