Oracle Server Manager User's Guide

The Latch Monitor

The Latch Monitor displays statistics for the latches in the system. Latches are low-level locks on shared internal structures.

The following figure illustrates the left-most columns of the Latch Monitor.

Figure 11 - 4. Latch Monitor

The Latch Monitor is described below:

Latch Name Name of the latch.
Holder PID Process identifier for process currently holding the latch.
Gets (Wait) Number of times, since the last sample, a process acquired the latch on its first attempt, but had to wait before acquiring it.
Misses (Wait) Number of times, since the last sample, a process acquired the latch after failing on its first attempt.
Sleeps (Wait) Number of times, since the last sample, a process went to sleep while waiting for the latch.
Gets (No Wait) Number of times, since the last sample, a process acquired the latch without waiting.
Misses (No Wait) Number of times, since the last sample, a process failed to acquire the latch and did not wait.

Attention: In the Latch Monitor you can only sort on the Latch Name and Holder PID columns.

SQL Worksheet Equivalent

To start the Latch Monitor from a SQL Worksheet, you can use the following Server Manager command:

	MONITOR LATCH

Required Views

To use the Latch Monitor, you must have access to:

V$LATCH

V$LATCHHOLDER

V$LATCHNAME

Latch Name	Name of the latch.
Holder PID	Process identifier for process currently holding the latch.
Gets (Wait)	Number of times, since the last sample, a process acquired the latch on its first attempt, but had to wait before acquiring it.
Misses (Wait)	Number of times, since the last sample, a process acquired the latch after failing on its first attempt.
Sleeps (Wait)	Number of times, since the last sample, a process went to sleep while waiting for the latch.
Gets (No Wait)	Number of times, since the last sample, a process acquired the latch without waiting.
Misses (No Wait)	Number of times, since the last sample, a process failed to acquire the latch and did not wait.