Change Details

During a recent high edit rate on wikidata, wikidata query service stopped to process updates. The updater logs show: ``` May 26 10:14:15 wdqs1001 bash[28413]: 10:14:15.070 [TailPoller] INFO o.w.q.r.t.c.TailingChangesPoller - Caught 477 missing updates, adding to the queue May 26 10:14:15 wdqs1001 bash[28413]: Exception in thread "TailPoller" java.lang.IllegalStateException: Queue full May 26 10:14:15 wdqs1001 bash[28413]: at java.util.AbstractQueue.add(AbstractQueue.java:98) May 26 10:14:15 wdqs1001 bash[28413]: at java.util.concurrent.ArrayBlockingQueue.add(ArrayBlockingQueue.java:312) May 26 10:14:15 wdqs1001 bash[28413]: at org.wikidata.query.rdf.tool.change.TailingChangesPoller.run(TailingChangesPoller.java:81) ``` Looking at [[ https://github.com/wikimedia/wikidata-query-rdf/blob/master/tools/src/main/java/org/wikidata/query/rdf/tool/change/TailingChangesPoller.java#L64-L96 | TailingChangesPoller ]], it looks like the case where the in ternal poller queue is full is not handled correctly. It might make sense to let the queue block in that case and let it apply back pressure on the producer (see [[ https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/ArrayBlockingQueue.html#offer(E,%20long,%20java.util.concurrent.TimeUnit) | ArrayBlockingQueue.offer() ]]).

During a recent high edit rate on wikidata, wikidata query service stopped to process updates. The updater logs show: ``` May 26 10:14:15 wdqs1001 bash[28413]: 10:14:15.070 [TailPoller] INFO o.w.q.r.t.c.TailingChangesPoller - Caught 477 missing updates, adding to the queue May 26 10:14:15 wdqs1001 bash[28413]: Exception in thread "TailPoller" java.lang.IllegalStateException: Queue full May 26 10:14:15 wdqs1001 bash[28413]: at java.util.AbstractQueue.add(AbstractQueue.java:98) May 26 10:14:15 wdqs1001 bash[28413]: at java.util.concurrent.ArrayBlockingQueue.add(ArrayBlockingQueue.java:312) May 26 10:14:15 wdqs1001 bash[28413]: at org.wikidata.query.rdf.tool.change.TailingChangesPoller.run(TailingChangesPoller.java:81) ``` Looking at [[ https://github.com/wikimedia/wikidata-query-rdf/blob/master/tools/src/main/java/org/wikidata/query/rdf/tool/change/TailingChangesPoller.java#L64-L96 | TailingChangesPoller ]], it looks like the case where the in ternal poller queue is full is not handled correctly. It might make sense to let the queue block in that case and let it apply back pressure on the producer (see [[ https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/BlockingQueue.html#put(E) | BlockingQueue.put() ]]).

During a recent high edit rate on wikidata, wikidata query service stopped to process updates. The updater logs show: ``` May 26 10:14:15 wdqs1001 bash[28413]: 10:14:15.070 [TailPoller] INFO o.w.q.r.t.c.TailingChangesPoller - Caught 477 missing updates, adding to the queue May 26 10:14:15 wdqs1001 bash[28413]: Exception in thread "TailPoller" java.lang.IllegalStateException: Queue full May 26 10:14:15 wdqs1001 bash[28413]: at java.util.AbstractQueue.add(AbstractQueue.java:98) May 26 10:14:15 wdqs1001 bash[28413]: at java.util.concurrent.ArrayBlockingQueue.add(ArrayBlockingQueue.java:312) May 26 10:14:15 wdqs1001 bash[28413]: at org.wikidata.query.rdf.tool.change.TailingChangesPoller.run(TailingChangesPoller.java:81) ``` Looking at [[ https://github.com/wikimedia/wikidata-query-rdf/blob/master/tools/src/main/java/org/wikidata/query/rdf/tool/change/TailingChangesPoller.java#L64-L96 | TailingChangesPoller ]], it looks like the case where the in ternal poller queue is full is not handled correctly. It might make sense to let the queue block in that case and let it apply back pressure on the producer (see [[ https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/ArrayBlockingQueue.html#offer(E,%20long,%20java.util.concurrent.TimeUnitput(E) | ArrayBlockingQueue.offerput() ]]).