Performance Tracing

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. expectedTime is an optional parameter, which specifies the expected duration of the trace.

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

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

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

Example

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