harmony 鸿蒙@ohos.hiTraceMeter (Performance Tracing)

2022-08-09
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@ohos.hiTraceMeter (Performance Tracing)

The hiTraceMeter module provides the functions of tracing service processes and monitoring the system performance. It provides the data needed for hiTraceMeter to carry out performance analysis.

NOTE
The initial APIs of this module are supported since API version 8. Newly added APIs will be marked with a superscript to indicate their earliest API version.

Modules to Import

import hiTraceMeter from '@ohos.hiTraceMeter';

hiTraceMeter.startTrace

startTrace(name: string, taskId: number): void

Starts a trace task.

If multiple trace tasks with the same name need to be performed at the same time or a trace task needs to be performed multiple times concurrently, different task IDs must be specified in startTrace.

If the trace tasks with the same name are not performed at the same time, the same taskId can be used. For a specific example, refer to an example in hiTraceMeter.finishTrace.

System capability: SystemCapability.HiviewDFX.HiTrace

Parameters

Name	Type	Mandatory	Description
name	string	Yes	Name of the trace task to start.
taskId	number	Yes	Task ID.

Example

hiTraceMeter.startTrace("myTestFunc", 1);

hiTraceMeter.finishTrace

finishTrace(name: string, taskId: number): void

Stops a trace task.

To stop a trace task, the values of name and task ID in finishTrace must be the same as those in startTrace.

System capability: SystemCapability.HiviewDFX.HiTrace

Parameters

Name	Type	Mandatory	Description
name	string	Yes	Name of the trace task to start.
taskId	number	Yes	Task ID.

Example

hiTraceMeter.finishTrace("myTestFunc", 1);

// Start track tasks with the same name concurrently.
hiTraceMeter.startTrace("myTestFunc", 1);
// Service flow
hiTraceMeter.startTrace("myTestFunc", 2);  // The second trace task starts while the first task is still running. The first and second tasks have the same name but different task IDs.
// Service flow
hiTraceMeter.finishTrace("myTestFunc", 1);
// Service flow
hiTraceMeter.finishTrace("myTestFunc", 2);

// Start track tasks with the same name at different times.
hiTraceMeter.startTrace("myTestFunc", 1);
// Service flow
hiTraceMeter.finishTrace("myTestFunc", 1);  // The first trace task ends.
// Service flow
hiTraceMeter.startTrace("myTestFunc", 1);   // The second trace task starts after the first task ends. The two tasks have the same name and task ID. 
// Service flow
hiTraceMeter.finishTrace("myTestFunc", 1);

hiTraceMeter.traceByValue

traceByValue(name: string, count: number): void

Traces the value changes of a variable.

System capability: SystemCapability.HiviewDFX.HiTrace

Parameters

Name	Type	Mandatory	Description
name	string	Yes	Name of the variable.
count	number	Yes	Value of the variable.

Example

let traceCount = 3;
hiTraceMeter.traceByValue("myTestCount", traceCount);
traceCount = 4;
hiTraceMeter.traceByValue("myTestCount", traceCount);
// Service flow