The static Atomics
.notify()
method notifies up some agents that are sleeping in the wait queue.
Note: This operation works with a shared Int32Array
only.
It will return 0
on non-shared ArrayBuffer
objects.
Syntax
Atomics.notify(typedArray, index, count)
Parameters
typedArray
- A shared
Int32Array
.
index
- The position in the
typedArray
to wake up on.
count
Optional
- The number of sleeping agents to notify. Defaults to
+Infinity
.
Return value
- Returns the number of woken up agents.
- Returns
0
, if a non-shared ArrayBuffer
object is used.
Exceptions
Examples
Using notify
Given a shared Int32Array
:
const sab = new SharedArrayBuffer(1024);
const int32 = new Int32Array(sab);
A reading thread is sleeping and waiting on location 0 which is expected to be 0. As long as that is true, it will not go on. However, once the writing thread has stored a new value, it will be notified by the writing thread and return the new value (123).
Atomics.wait(int32, 0, 0);
console.log(int32[0]); // 123
A writing thread stores a new value and notifies the waiting thread once it has written:
console.log(int32[0]); // 0;
Atomics.store(int32, 0, 123);
Atomics.notify(int32, 0, 1);
Specifications
Browser compatibility
| Desktop | Mobile | Server |
---|
| Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | Android webview | Chrome for Android | Firefox for Android | Opera for Android | Safari on iOS | Samsung Internet | Node.js |
---|
notify | Chrome
Full support
68-
Full support
68
-
No support
60 — 63
- Notes Chrome disabled
SharedArrayBuffer on January 5, 2018 to help reduce the efficacy of speculative side-channel attacks. This was a temporary removal while mitigations were put in place. - Alternate Name Uses the non-standard name:
wake
| Edge
Full support
79 | Firefox
Full support
78-
Full support
78
-
Full support
63
- Notes Support was disabled by default to mitigate speculative execution side-channel attacks (Mozilla Security Blog).
- Disabled From version 63: this feature is behind the
javascript.options.shared_memory preference (needs to be set to true ). To change preferences in Firefox, visit about:config. -
Full support
57
Notes Alternate Name Disabled - Notes Support was disabled by default to mitigate speculative execution side-channel attacks (Mozilla Security Blog).
- Alternate Name Uses the non-standard name:
wake - Disabled From version 57: this feature is behind the
javascript.options.shared_memory preference (needs to be set to true ). To change preferences in Firefox, visit about:config. -
No support
55 — 57
-
No support
48 — 55
- Disabled From version 48 until version 55 (exclusive): this feature is behind the
javascript.options.shared_memory preference (needs to be set to true ). To change preferences in Firefox, visit about:config. -
No support
46 — 48
Notes Alternate Name Disabled - Notes The
count parameter defaults to 0 instead of the later-specified +Infinity . - Alternate Name Uses the non-standard name:
futexWake - Disabled From version 46 until version 48 (exclusive): this feature is behind the
javascript.options.shared_memory preference (needs to be set to true ). To change preferences in Firefox, visit about:config.
| IE
No support
No | Opera
No support
No | Safari
No support
10.1 — 11.1-
No support
10.1 — 11.1
- Alternate Name Uses the non-standard name:
wake
| WebView Android
No support
60 — 63-
No support
60 — 63
- Notes Chrome disabled
SharedArrayBuffer on January 5, 2018 to help reduce the efficacy of speculative side-channel attacks. This is intended as a temporary measure until other mitigations are in place. - Alternate Name Uses the non-standard name:
wake
| Chrome Android
No support
60 — 63-
No support
60 — 63
- Notes Chrome disabled
SharedArrayBuffer on January 5, 2018 to help reduce the efficacy of speculative side-channel attacks. This is intended as a temporary measure until other mitigations are in place. - Alternate Name Uses the non-standard name:
wake
| Firefox Android
Full support
63-
Full support
63
- Notes Support was disabled by default to mitigate speculative execution side-channel attacks (Mozilla Security Blog).
- Disabled From version 63: this feature is behind the
javascript.options.shared_memory preference (needs to be set to true ). To change preferences in Firefox, visit about:config. -
Full support
57
Notes Alternate Name Disabled - Notes Support was disabled by default to mitigate speculative execution side-channel attacks (Mozilla Security Blog).
- Alternate Name Uses the non-standard name:
wake - Disabled From version 57: this feature is behind the
javascript.options.shared_memory preference (needs to be set to true ). To change preferences in Firefox, visit about:config. -
No support
55 — 57
-
No support
48 — 55
- Disabled From version 48 until version 55 (exclusive): this feature is behind the
javascript.options.shared_memory preference (needs to be set to true ). To change preferences in Firefox, visit about:config. -
No support
46 — 48
Notes Alternate Name Disabled - Notes The
count parameter defaults to 0 instead of the later-specified +Infinity . - Alternate Name Uses the non-standard name:
futexWake - Disabled From version 46 until version 48 (exclusive): this feature is behind the
javascript.options.shared_memory preference (needs to be set to true ). To change preferences in Firefox, visit about:config.
| Opera Android
No support
No | Safari iOS
No support
10.3 — 11.3 | Samsung Internet Android
No support
No-
No support
No
- Notes Chrome disabled
SharedArrayBuffer on January 5, 2018 to help reduce the efficacy of speculative side-channel attacks. This is intended as a temporary measure until other mitigations are in place. - Alternate Name Uses the non-standard name:
wake
| nodejs
Full support
8.10.0-
Full support
8.10.0
- Alternate Name Uses the non-standard name:
wake
|
---|
Legend
-
Full support
- Full support
-
No support
- No support
- See implementation notes.
- See implementation notes.
- User must explicitly enable this feature.
- User must explicitly enable this feature.
- Uses a non-standard name.
- Uses a non-standard name.
See also