@ohos.bytrace (Performance Tracing)

NOTE

• The APIs of this module are no longer maintained since API version 8. It is recommended that you use the APIs of hiTraceMeter instead.
• The initial APIs of this module are supported since API version 7. Newly added APIs will be marked with a superscript to indicate their earliest API version.

Modules to Import

import bytrace from '@ohos.bytrace';

bytrace.startTrace

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

Marks the start of a timeslice trace task.

NOTE

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 details, see the bytrace.finishTrace example.

System capability: SystemCapability.Developtools.Bytrace

Parameters

Example

bytrace.startTrace("myTestFunc", 1);
bytrace.startTrace("myTestFunc", 1, 5); // The expected duration of the trace is 5 ms.

bytrace.finishTrace

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

Marks the end of a timeslice trace task.

NOTE

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.Developtools.Bytrace

Parameters

Example

bytrace.finishTrace("myTestFunc", 1);

// Start track tasks with the same name concurrently.
bytrace.startTrace("myTestFunc", 1);
// Service flow
bytrace.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
bytrace.finishTrace("myTestFunc", 1);
// Service flow
bytrace.finishTrace("myTestFunc", 2);

// Start track tasks with the same name at different times.
bytrace.startTrace("myTestFunc", 1);
// Service flow
bytrace.finishTrace("myTestFunc", 1); // The first trace task ends.
// Service flow
bytrace.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
bytrace.finishTrace("myTestFunc", 1);

bytrace.traceByValue

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

Defines the variable that indicates the number of timeslice trace tasks.

System capability: SystemCapability.HiviewDFX.HiTrace

Parameters

Example

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