[SOLR-2308] Race condition still exists in StreamingUpdateSolrServer which could cause it to hang

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.4.1
• Fix Version/s: 3.1, 4.0-ALPHA
• Component/s: clients - java
• Assignee: Unassigned
• Reporter: Johannes
• Created: 06/Jan/11 23:22
• Updated: 18/Jan/12 18:16
• Resolved: 30/Jan/11 01:48

Description

We are still seeing the same issue as SOLR-1711 & SOLR-1885 with Solr1.4.1
We get into this situation when all the runner threads die due to a broken pipe, while the BlockingQueue is still full. All of the producer threads are all blocked on the BlockingQueue.put() method. Since the runners are spawned by the producers, which are all blocked, runner threads never get created to drain the queue.

Here's a potential fix. In the runner code, replace these lines:

// remove it from the list of running things...
synchronized (runners) {
    runners.remove( this );
}

with these lines:

// remove it from the list of running things unless we are the last runner and the queue is full...
synchronized (runners) {
    if (runners.size() == 1 && queue.remainingCapacity() == 0) {
        // keep this runner alive
        scheduler.execute(this);
    } else {
        runners.remove( this );
    }
}

Issue Links

• duplicates: SOLR-1711 Race condition in org/apache/solr/client/solrj/impl/StreamingUpdateSolrServer.java