Connection Pool statistics look low and database shows more than expected connections

Environment

• Red Hat JBoss Enterprise Application Platform prior to 6.4.5
• prefill=true as defined in
  • jboss-as-datasources_1_1.xsd
  • jboss-as-datasources_1_2.xsd

Issue

• JDBC connection leak
• apps are closing connections properly still lot of inactive session at DB side
• causing slow performance and eventually bringing down the application and DB
• Datasource statistics ActiveCount is dramatically different from the open connections as reported by the database server
• The datasource pool has prefill enabled

Resolution

• This issue¹ is resolved in This content is not included.EAP 6.4 cumulative patch (CP) 5 and later releases. Production systems should use the latest available cumulative patch.
• For older releases (not using current patch levels), set prefill=false on the affected datasource .

Root Cause

This is a known defect (Content from issues.jboss.org is not included.JBJCA-1276).

Diagnostic Steps

grep'ing a TRACE log for multiple occurrences of managed connection pool instances can be done to determine if JBJCA-1276 is affecting an evironment. [1] shows an environment that needs prefill = false or EAP 6.4.5 applied. [2] shows a healthy environment.

[1]

$ grep -o SemaphoreArrayListManagedConnectionPool.*<pool name> server.log | sort -u
SemaphoreArrayListManagedConnectionPool@41093a00[pool=<pool name>
<multiple entries>
...

[2]

$ grep -o SemaphoreArrayListManagedConnectionPool.*<pool name> server.log | sort -u
SemaphoreArrayListManagedConnectionPool@41093a00[pool=<pool name>
<no more hits returned>

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