Javascript acting multitheaded in Firefox
Everything relevant on the internet I've read indicates that Javascript is single-threaded (aside from Web Workers, which run in a different global context and shouldn't be able to directly affect the state in the main thread). However, while debugging some code, I noticed that even while I was paused on such-and-such a line, variables kept changing, even when I didn't step over lines of code. Investigating further, I noticed that, again, even while paused in the debugger (and I wasn't touching anything), logs were logged and errors were thrown every second according to a timeout that had been set.
I am using OS: Windows 10 Enterprise, version 1803, OS build 17134.407.
I experienced the issue in Firefox 63.0.1 (64-bit).
When I tried it in Chrome 70.0.3538.102 (Official Build) (64-bit), however, the issue did not occur - pausing in the debugger appeared to pause all computation, as expected.
I can't provide any useful code, because 1. it's company code, and 2. it's a multithreading style problem, which makes it very difficult to narrow down to any given section of code. Things that might be relevant, aside from aforementioned browser differences: it's an AngularJS application, served to the browser from NodeJS. We're using $interval(), timeout(), $http, and Stomp websocket connections.
According to my understanding, this apparently multithreaded behavior should be impossible. How could this happen?
javascript multithreading
google-chrome firefox asked Nov 24 '18 at 1:48
ErhannisErhannis
2,54711428
add a comment |
Everything relevant on the internet I've read indicates that Javascript is single-threaded (aside from Web Workers, which run in a different global context and shouldn't be able to directly affect the state in the main thread). However, while debugging some code, I noticed that even while I was paused on such-and-such a line, variables kept changing, even when I didn't step over lines of code. Investigating further, I noticed that, again, even while paused in the debugger (and I wasn't touching anything), logs were logged and errors were thrown every second according to a timeout that had been set.
I am using OS: Windows 10 Enterprise, version 1803, OS build 17134.407.
I experienced the issue in Firefox 63.0.1 (64-bit).
When I tried it in Chrome 70.0.3538.102 (Official Build) (64-bit), however, the issue did not occur - pausing in the debugger appeared to pause all computation, as expected.
I can't provide any useful code, because 1. it's company code, and 2. it's a multithreading style problem, which makes it very difficult to narrow down to any given section of code. Things that might be relevant, aside from aforementioned browser differences: it's an AngularJS application, served to the browser from NodeJS. We're using $interval(), timeout(), $http, and Stomp websocket connections.
According to my understanding, this apparently multithreaded behavior should be impossible. How could this happen?
javascript multithreading
google-chrome firefox asked Nov 24 '18 at 1:48
ErhannisErhannis
2,54711428
If there is any multiprocessing going on, it is likely the browser's internal operations that are multithreaded for this anomaly and not the JS runtime. So this seems simply like Mozilla's debugger works differently than Chrome's.
– Randy Casburn
Nov 24 '18 at 2:24
@RandyCasburn Perhaps, depending on what you mean. If the debugger is to be believed, there is more than one thread of execution. I can step through code in one place, all the while code continues to be executed somewhere else. It seems like this would be an actual bug in Firefox's debugger, rather than a simple difference of operation - if invoking the debugger invisibly and significantly breaks one of the fundamental principles of programming in Javascript, that seems like a bug to me.
– Erhannis
Nov 24 '18 at 2:44
Then report it after you read the third essential quality here: developer.mozilla.org/en-US/docs/Tools/Debugger-API
– Randy Casburn
Nov 24 '18 at 2:51
add a comment |
Everything relevant on the internet I've read indicates that Javascript is single-threaded (aside from Web Workers, which run in a different global context and shouldn't be able to directly affect the state in the main thread). However, while debugging some code, I noticed that even while I was paused on such-and-such a line, variables kept changing, even when I didn't step over lines of code. Investigating further, I noticed that, again, even while paused in the debugger (and I wasn't touching anything), logs were logged and errors were thrown every second according to a timeout that had been set.
I am using OS: Windows 10 Enterprise, version 1803, OS build 17134.407.
I experienced the issue in Firefox 63.0.1 (64-bit).
When I tried it in Chrome 70.0.3538.102 (Official Build) (64-bit), however, the issue did not occur - pausing in the debugger appeared to pause all computation, as expected.
I can't provide any useful code, because 1. it's company code, and 2. it's a multithreading style problem, which makes it very difficult to narrow down to any given section of code. Things that might be relevant, aside from aforementioned browser differences: it's an AngularJS application, served to the browser from NodeJS. We're using $interval(), timeout(), $http, and Stomp websocket connections.
According to my understanding, this apparently multithreaded behavior should be impossible. How could this happen?
javascript multithreading
google-chrome firefox asked Nov 24 '18 at 1:48
ErhannisErhannis
2,54711428
Everything relevant on the internet I've read indicates that Javascript is single-threaded (aside from Web Workers, which run in a different global context and shouldn't be able to directly affect the state in the main thread). However, while debugging some code, I noticed that even while I was paused on such-and-such a line, variables kept changing, even when I didn't step over lines of code. Investigating further, I noticed that, again, even while paused in the debugger (and I wasn't touching anything), logs were logged and errors were thrown every second according to a timeout that had been set.
I am using OS: Windows 10 Enterprise, version 1803, OS build 17134.407.
I experienced the issue in Firefox 63.0.1 (64-bit).
When I tried it in Chrome 70.0.3538.102 (Official Build) (64-bit), however, the issue did not occur - pausing in the debugger appeared to pause all computation, as expected.
I can't provide any useful code, because 1. it's company code, and 2. it's a multithreading style problem, which makes it very difficult to narrow down to any given section of code. Things that might be relevant, aside from aforementioned browser differences: it's an AngularJS application, served to the browser from NodeJS. We're using $interval(), timeout(), $http, and Stomp websocket connections.
According to my understanding, this apparently multithreaded behavior should be impossible. How could this happen?
javascript multithreading
google-chrome firefox javascript multithreading
google-chrome firefox asked Nov 24 '18 at 1:48
ErhannisErhannis
2,54711428
asked Nov 24 '18 at 1:48
ErhannisErhannis
2,54711428
asked Nov 24 '18 at 1:48
ErhannisErhannis
2,54711428
asked Nov 24 '18 at 1:48
ErhannisErhannis
2,54711428
asked Nov 24 '18 at 1:48
ErhannisErhannis
2,54711428
2,54711428
If there is any multiprocessing going on, it is likely the browser's internal operations that are multithreaded for this anomaly and not the JS runtime. So this seems simply like Mozilla's debugger works differently than Chrome's.
– Randy Casburn
Nov 24 '18 at 2:24
@RandyCasburn Perhaps, depending on what you mean. If the debugger is to be believed, there is more than one thread of execution. I can step through code in one place, all the while code continues to be executed somewhere else. It seems like this would be an actual bug in Firefox's debugger, rather than a simple difference of operation - if invoking the debugger invisibly and significantly breaks one of the fundamental principles of programming in Javascript, that seems like a bug to me.
– Erhannis
Nov 24 '18 at 2:44
Then report it after you read the third essential quality here: developer.mozilla.org/en-US/docs/Tools/Debugger-API
– Randy Casburn
Nov 24 '18 at 2:51
add a comment |
If there is any multiprocessing going on, it is likely the browser's internal operations that are multithreaded for this anomaly and not the JS runtime. So this seems simply like Mozilla's debugger works differently than Chrome's.
– Randy Casburn
Nov 24 '18 at 2:24
@RandyCasburn Perhaps, depending on what you mean. If the debugger is to be believed, there is more than one thread of execution. I can step through code in one place, all the while code continues to be executed somewhere else. It seems like this would be an actual bug in Firefox's debugger, rather than a simple difference of operation - if invoking the debugger invisibly and significantly breaks one of the fundamental principles of programming in Javascript, that seems like a bug to me.
– Erhannis
Nov 24 '18 at 2:44
Then report it after you read the third essential quality here: developer.mozilla.org/en-US/docs/Tools/Debugger-API
– Randy Casburn
Nov 24 '18 at 2:51
If there is any multiprocessing going on, it is likely the browser's internal operations that are multithreaded for this anomaly and not the JS runtime. So this seems simply like Mozilla's debugger works differently than Chrome's.
– Randy Casburn
Nov 24 '18 at 2:24
If there is any multiprocessing going on, it is likely the browser's internal operations that are multithreaded for this anomaly and not the JS runtime. So this seems simply like Mozilla's debugger works differently than Chrome's.
– Randy Casburn
Nov 24 '18 at 2:24
@RandyCasburn Perhaps, depending on what you mean. If the debugger is to be believed, there is more than one thread of execution. I can step through code in one place, all the while code continues to be executed somewhere else. It seems like this would be an actual bug in Firefox's debugger, rather than a simple difference of operation - if invoking the debugger invisibly and significantly breaks one of the fundamental principles of programming in Javascript, that seems like a bug to me.
– Erhannis
Nov 24 '18 at 2:44
@RandyCasburn Perhaps, depending on what you mean. If the debugger is to be believed, there is more than one thread of execution. I can step through code in one place, all the while code continues to be executed somewhere else. It seems like this would be an actual bug in Firefox's debugger, rather than a simple difference of operation - if invoking the debugger invisibly and significantly breaks one of the fundamental principles of programming in Javascript, that seems like a bug to me.
– Erhannis
Nov 24 '18 at 2:44
Then report it after you read the third essential quality here: developer.mozilla.org/en-US/docs/Tools/Debugger-API
– Randy Casburn
Nov 24 '18 at 2:51
Then report it after you read the third essential quality here: developer.mozilla.org/en-US/docs/Tools/Debugger-API
– Randy Casburn
Nov 24 '18 at 2:51
add a comment |
1 Answer
1
active
oldest
votes
Nodejs in fact is not single threaded. It has basically two parts:
- Javascript part. Basically Event loop processes (single threaded).
- C++ part (libuv library), thanks to V8. This part implements a thread pool with multiple thread to compute costly operations. This way we don't block the event loop.
So, maybe you can check all the modules that you are using and check their implementation. Anyone implemented in C++ uses the thread pool on the background.
answered Dec 2 '18 at 16:31
Dr. CooperDr. Cooper
12
Hmm. Except, it appears multithreaded even on the client-side. Are the C++ libraries executed client-side? I'd be very surprised; that seems like a very dangerous thing to allow a website to execute.
– Erhannis
Dec 4 '18 at 5:42
add a comment |
Your Answer
StackExchange.ifUsing("editor", function () {
StackExchange.using("externalEditor", function () {
StackExchange.using("snippets", function () {
StackExchange.snippets.init();
});
});
}, "code-snippets");
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "1"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53454511%2fjavascript-acting-multitheaded-in-firefox%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
Nodejs in fact is not single threaded. It has basically two parts:
- Javascript part. Basically Event loop processes (single threaded).
- C++ part (libuv library), thanks to V8. This part implements a thread pool with multiple thread to compute costly operations. This way we don't block the event loop.
So, maybe you can check all the modules that you are using and check their implementation. Anyone implemented in C++ uses the thread pool on the background.
answered Dec 2 '18 at 16:31
Dr. CooperDr. Cooper
12
Hmm. Except, it appears multithreaded even on the client-side. Are the C++ libraries executed client-side? I'd be very surprised; that seems like a very dangerous thing to allow a website to execute.
– Erhannis
Dec 4 '18 at 5:42
add a comment |
Nodejs in fact is not single threaded. It has basically two parts:
- Javascript part. Basically Event loop processes (single threaded).
- C++ part (libuv library), thanks to V8. This part implements a thread pool with multiple thread to compute costly operations. This way we don't block the event loop.
So, maybe you can check all the modules that you are using and check their implementation. Anyone implemented in C++ uses the thread pool on the background.
answered Dec 2 '18 at 16:31
Dr. CooperDr. Cooper
12
Hmm. Except, it appears multithreaded even on the client-side. Are the C++ libraries executed client-side? I'd be very surprised; that seems like a very dangerous thing to allow a website to execute.
– Erhannis
Dec 4 '18 at 5:42
add a comment |
Nodejs in fact is not single threaded. It has basically two parts:
- Javascript part. Basically Event loop processes (single threaded).
- C++ part (libuv library), thanks to V8. This part implements a thread pool with multiple thread to compute costly operations. This way we don't block the event loop.
So, maybe you can check all the modules that you are using and check their implementation. Anyone implemented in C++ uses the thread pool on the background.
answered Dec 2 '18 at 16:31
Dr. CooperDr. Cooper
12
Nodejs in fact is not single threaded. It has basically two parts:
- Javascript part. Basically Event loop processes (single threaded).
- C++ part (libuv library), thanks to V8. This part implements a thread pool with multiple thread to compute costly operations. This way we don't block the event loop.
So, maybe you can check all the modules that you are using and check their implementation. Anyone implemented in C++ uses the thread pool on the background.
answered Dec 2 '18 at 16:31
Dr. CooperDr. Cooper
12
answered Dec 2 '18 at 16:31
Dr. CooperDr. Cooper
12
answered Dec 2 '18 at 16:31
Dr. CooperDr. Cooper
12
answered Dec 2 '18 at 16:31
Dr. CooperDr. Cooper
12
12
Hmm. Except, it appears multithreaded even on the client-side. Are the C++ libraries executed client-side? I'd be very surprised; that seems like a very dangerous thing to allow a website to execute.
– Erhannis
Dec 4 '18 at 5:42
add a comment |
Hmm. Except, it appears multithreaded even on the client-side. Are the C++ libraries executed client-side? I'd be very surprised; that seems like a very dangerous thing to allow a website to execute.
– Erhannis
Dec 4 '18 at 5:42
Hmm. Except, it appears multithreaded even on the client-side. Are the C++ libraries executed client-side? I'd be very surprised; that seems like a very dangerous thing to allow a website to execute.
– Erhannis
Dec 4 '18 at 5:42
Hmm. Except, it appears multithreaded even on the client-side. Are the C++ libraries executed client-side? I'd be very surprised; that seems like a very dangerous thing to allow a website to execute.
– Erhannis
Dec 4 '18 at 5:42
add a comment |
Thanks for contributing an answer to Stack Overflow!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53454511%2fjavascript-acting-multitheaded-in-firefox%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
If there is any multiprocessing going on, it is likely the browser's internal operations that are multithreaded for this anomaly and not the JS runtime. So this seems simply like Mozilla's debugger works differently than Chrome's.
– Randy Casburn
Nov 24 '18 at 2:24
@RandyCasburn Perhaps, depending on what you mean. If the debugger is to be believed, there is more than one thread of execution. I can step through code in one place, all the while code continues to be executed somewhere else. It seems like this would be an actual bug in Firefox's debugger, rather than a simple difference of operation - if invoking the debugger invisibly and significantly breaks one of the fundamental principles of programming in Javascript, that seems like a bug to me.
– Erhannis
Nov 24 '18 at 2:44
Then report it after you read the third essential quality here: developer.mozilla.org/en-US/docs/Tools/Debugger-API
– Randy Casburn
Nov 24 '18 at 2:51