[SOLR-15009] DirectoryFactory exists masks IOExceptions

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 8.4.1
• Fix Version/s: 8.8, 9.0
• Labels: NPE
• Assignee: Mike Drob
• Reporter: Mike Drob
• Created: 20/Nov/20 21:22
• Updated: 12/May/22 00:26
• Resolved: 30/Nov/20 18:29

Description

This NPE was seen on a cluster running 8.4.1 -

o.a.s.h.RequestHandlerBase java.lang.NullPointerException
	at org.apache.solr.core.StandardDirectoryFactory.exists(StandardDirectoryFactory.java:92)
	at org.apache.solr.core.SolrCore.getIndexSize(SolrCore.java:462)
	at org.apache.solr.core.SolrCore.lambda$initializeMetrics$8(SolrCore.java:1200)
	at org.apache.solr.metrics.SolrMetricManager$GaugeWrapper.getValue(SolrMetricManager.java:711)
	at org.apache.solr.util.stats.MetricUtils.convertGauge(MetricUtils.java:488)
	at org.apache.solr.util.stats.MetricUtils.convertMetric(MetricUtils.java:274)
	at org.apache.solr.util.stats.MetricUtils.lambda$toMaps$4(MetricUtils.java:213)

The problem comes from an IOException from list, which gets turned into a null return. In this case, we do want the IOException to bubble so that we can catch and log in getIndexSize.

Aside from that, if all we really care about is whether there are files, then we could do a much more efficient check than requiring the whole directory to be listed. This is especially problematic when the directory is large or remote.

Issue Links

• links to: GitHub Pull Request #2092