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Profiler

Dependencies: Runtime, Debugger

Commands

Profiler.disable

Profiler.enable

Profiler.getBestEffortCoverage

Collect coverage data for the current isolate. The coverage data may be incomplete due to
garbage collection.

Return Object
Name Type Description
result array<ScriptCoverage> Coverage data for the current isolate.

Profiler.setSamplingInterval

Changes CPU profiler sampling interval. Must be called before CPU profiles recording started.

Parameters
Name Type Description
interval integer New sampling interval in microseconds.

Profiler.start

Profiler.startPreciseCoverage

Enable precise code coverage. Coverage data for JavaScript executed before enabling precise code
coverage may be incomplete. Enabling prevents running optimized code and resets execution
counters.

Parameters
Name Type Description
callCount (optional) boolean Collect accurate call counts beyond simple 'covered' or 'not covered'.
detailed (optional) boolean Collect block-based coverage.
allowTriggeredUpdates (optional) boolean Allow the backend to send updates on its own initiative
Return Object
Name Type Description
timestamp number Monotonically increasing time (in seconds) when the coverage update was taken in the backend.

Profiler.stop

Return Object
Name Type Description
profile Profile Recorded profile.

Profiler.stopPreciseCoverage

Disable precise code coverage. Disabling releases unnecessary execution count records and allows
executing optimized code.

Profiler.takePreciseCoverage

Collect coverage data for the current isolate, and resets execution counters. Precise code
coverage needs to have started.

Return Object
Name Type Description
result array<ScriptCoverage> Coverage data for the current isolate.
timestamp number Monotonically increasing time (in seconds) when the coverage update was taken in the backend.

Events

Profiler.consoleProfileFinished

Parameters
Name Type Description
id string
location Debugger.Location Location of console.profileEnd().
profile Profile
title (optional) string Profile title passed as an argument to console.profile().

Profiler.consoleProfileStarted

Sent when new profile recording is started using console.profile() call.

Parameters
Name Type Description
id string
location Debugger.Location Location of console.profile().
title (optional) string Profile title passed as an argument to console.profile().

Profiler.preciseCoverageDeltaUpdate

Experimental

Reports coverage delta since the last poll (either from an event like this, or from
`takePreciseCoverage` for the current isolate. May only be sent if precise code
coverage has been started. This event can be trigged by the embedder to, for example,
trigger collection of coverage data immediately at a certain point in time.

Parameters
Name Type Description
timestamp number Monotonically increasing time (in seconds) when the coverage update was taken in the backend.
occasion string Identifier for distinguishing coverage events.
result array<ScriptCoverage> Coverage data for the current isolate.

Types

ProfileNode

(object)

Profile node. Holds callsite information, execution statistics and child nodes.

Properties
Name Type Description
id integer Unique id of the node.
callFrame Runtime.CallFrame Function location.
hitCount (optional) integer Number of samples where this node was on top of the call stack.
children (optional) array<integer> Child node ids.
deoptReason (optional) string The reason of being not optimized. The function may be deoptimized or marked as don't
optimize.
positionTicks (optional) array<PositionTickInfo> An array of source position ticks.

Profile

(object)

Profile.

Properties
Name Type Description
nodes array<ProfileNode> The list of profile nodes. First item is the root node.
startTime number Profiling start timestamp in microseconds.
endTime number Profiling end timestamp in microseconds.
samples (optional) array<integer> Ids of samples top nodes.
timeDeltas (optional) array<integer> Time intervals between adjacent samples in microseconds. The first delta is relative to the
profile startTime.

PositionTickInfo

(object)

Specifies a number of samples attributed to a certain source position.

Properties
Name Type Description
line integer Source line number (1-based).
ticks integer Number of samples attributed to the source line.

CoverageRange

(object)

Coverage data for a source range.

Properties
Name Type Description
startOffset integer JavaScript script source offset for the range start.
endOffset integer JavaScript script source offset for the range end.
count integer Collected execution count of the source range.

FunctionCoverage

(object)

Coverage data for a JavaScript function.

Properties
Name Type Description
functionName string JavaScript function name.
ranges array<CoverageRange> Source ranges inside the function with coverage data.
isBlockCoverage boolean Whether coverage data for this function has block granularity.

ScriptCoverage

(object)

Coverage data for a JavaScript script.

Properties
Name Type Description
scriptId Runtime.ScriptId JavaScript script id.
url string JavaScript script name or url.
functions array<FunctionCoverage> Functions contained in the script that has coverage data.

Summary