Intermittent Application Hangs Occur On An Exalogic Physical Or Virtual Server Due To A Race Condition That Occurs While Updating Memory Mapped Files Located Under NFS (Doc ID 1924645.1)

Last updated on MARCH 03, 2016

Applies to:

Oracle Exalogic Elastic Cloud Software - Version 2.0.0.0.0 and later
Information in this document applies to any platform.

Symptoms

On Exalogic deployed in a Physical or Virtual configuration running Siebel or Oracle HTTP Server (Powered By Apache) as a standalone component or as part of another product such as E-Business Suite or Oracle Fusion Middleware, the following issues are encountered intermittently:

Upon inspecting /var/log/messages, the following logs are observed shortly before the hang or crash:

 

The above log messages indicate the following:

  1. The "flush" processes have become unresponsive

    • Functions listed at the top of the Call Trace, such as "io_schedule", indicate that the process is blocked waiting to perform an I/O related activity
    • Subsequent functions within the Call Trace, such as "nfs_writepages", indicate that the I/O activity is NFS related.

  2. Presence of other processes (such as "siebsvc" or "httpd") which have become blocked while attempting to update pages related to memory mapped files

    • The process names of the other block processes may vary
    • At the top of the Call Trace the function "io_schedule" shows these processes also waiting to perform an I/O related activity
    • Function calls listed subsequently in the stack trace include "nfs_wb_page" (indicating that the blocked I/O activity is NFS related) and "handle_mm_fault" (indicating that the NFS activity is related to the update of a memory mapped file)

 

Cause

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