I just posted a simple change on SOLR-126... it cancels any pending activity when you close the UpdateHandler
public void close() throws IOException { log.info("closing " + this); iwCommit.lock(); try{ // cancel any pending operations if( tracker.pending != null ) { tracker.pending.cancel( true ); tracker.pending = null; } doDeletions(); closeSearcher(); closeWriter(); } finally { iwCommit.unlock(); } log.info("closed " + this); }