Use the
Performance
panel to profile the performance of
Node.js
and
Deno
applications.
What's a CPU profile?
A CPU profile is a report that shows how the CPU was used over a period of time. It can show which programs were using the most CPU time, which processes were running, and how much time was spent in each state. With CPU profiles, you can identify performance bottlenecks and optimize CPU resource utilization.
In the command line, run:
Node.js
node --inspect
file-name
.js
Deno
deno --inspect
file-name
.js
Connect to DevTools for Node in one of the following ways:
Profile the CPU
To profile the CPU, open the
Performance
panel and click the
radio_button_checked
Record
button two times to start and end profiling.
Analyze profiling results
After you stop the recording, the
Performance
panel organizes and displays data about the recording in a "profile". Use the following tabs to analyze the profiling data:
Timeline overview
. Located at the top under the activity bar. Shows CPU and NET activity charts on a timeline. Use it to identify performance bottlenecks.
Bottom-Up
: Use this tab to inspect a
selected portion of the recording
and see aggregated time spent on individual activities.
Call Tree
: This tab displays the root activities of a
selected portion of the recording
. Root activities also have their call stacks nested. Use this tab to identify which activity is causing the most work.
Event Log
: This tab lists activities from a
selected portion of the recording
in the order that they occurred.
Profile with the
console.profile()
command
DevTools lets you profile JavaScript CPU performance with the
console.profile()
command. You can add this command to your code and then run the file, or copy and paste your code into the
Console
. The
Performance
panel will show you the results.
To use this command, follow these steps:
Enclose your code with
console.profile()
and
console.profileEnd()
, for example:
console.profile( profile ${i} );
// Code to be profiled
doSomething();
console.profileEnd();
Run your code in one of two ways:
If you're using the
Console
,
open DevTools for Node
, paste your code to the
Console
, and press
Enter
.
In the command line, run:
Node.js
node --inspect
file-name
.js
Deno
deno --inspect
file-name
.js
Then
open DevTools for Node
.
Once the profile is completed, the result will be shown in the
Performance
panel automatically.