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1.4.3 Diagnostic and Monitoring Capabilities

MySQL 5.5 provides improved access to execution and performance information. Diagnostic improvements include Performance Schema, Dtrace probes, expanded SHOW ENGINE INNODB STATUS output, Debug Sync, and a new status variable.

Performance Schema

Performance Schema is a feature for monitoring MySQL Server execution at a low level. See Chapter 22, MySQL Performance Schema.

DTrace Support

The DTrace probes work on Solaris, OS X, and FreeBSD. For information on using DTrace in MySQL, see Section 5.7, “Tracing mysqld Using DTrace”.


The output from SHOW ENGINE INNODB STATUS includes more information due to changes made for InnoDB Plugin. A description of revisions to statement output follows.

A new BACKGROUND THREAD section has srv_master_thread lines that show work done by the main background thread.

srv_master_thread loops: 53 1_second, 44 sleeps, 5 10_second, 7 background,
  7 flush
srv_master_thread log flush and writes: 48

The SEMAPHORES section includes a line to show the number of spinlock rounds per OS wait for a mutex.

Spin rounds per wait: 0.00 mutex, 20.00 RW-shared, 0.00 RW-excl

Debug Sync

The Debug Sync facility provides synchronization points for debugging, see MySQL Internals: Test Synchronization.

New Status Variable

The Innodb_have_atomic_builtins status variable provides information about availability of atomic instructions; see Section 1.4.1, “Scalability Improvements”.

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