Worker was destroyed

[David-moonsite]

Hi ,
sometimes i get "Worker was destroyed",
why is it happening

[phuocng]

sometimes

Can you let me know how to reproduce the issue?

[David-moonsite]

• create list with 10 buttons
• each button should open same modal with different Pdf Document
• click on different button to open modal and close it several times

[phuocng]

Where do you put the Worker?
It's recommended to put the Worker in the page, not in the modal.

[David-moonsite]

In modal ,
i need to show pdf document in modal.

[phuocng]

You should put the Worker in the page. In the Setting up the worker section, it mentions that we should place the Worker at the root:

const App = () => {
    return (
        <Worker
            workerUrl="https://unpkg.com/pdfjs-dist@2.5.207/build/pdf.worker.min.js"
        >
            ...
        </Worker>
    );
};

render(<App />, document.getElementById('root'));

[David-moonsite]

OK,
i did it, same issue

[phuocng]

@phuoc-ng Found related issues
https://github.com/mozilla/pdf.js/blob/master/test/unit/api_spec.js#L425

[WiemSoued]

Same issue, even when the worker is placed at the root.
The message "Worker was destroyed" is shown then the pdf file is loaded.
Is there an explanation?

[WiemSoued]

The issue is that the pdf.worker.min.js is called multiple times so the message "Worker was destroyed" is present while the pdf.worker.min.js is pending.
Is there any explanation for this behavior?

[WiemSoued]

For anyone who needs this in the future,
the issue is caused when you use multiple workers on the same page.
If it's destroyed while still being initialized, you run into problems. The same happens if it's initialized while an earlier instance is still being destroyed.
I solved this by using a TimeOut.

[phuocng]

@David-moonsite
@WiemSoued
This issue is fixed in #424. I'll include the fix in v2.3.2!

Reason

By default, for each document pdf.js will create a web worker to parse and render the document.
The worker then will be reused if the it sees the same document.

Let's say that we have 3 documents, and there are 2 buttons, Next and Previous to load the previous and next document.
Initially, pdf.js will create a worker with id of d_0 for the first document.

When user clicks the Next button, it then destroys the d_0 worker, and create a new worker, d_1 to parse the second document.
If user clicks the Previous button, it will reuse the d_0 worker but the worker was destroyed.

In order to fix that, I create and destroy the worker manually.

[phuocng]

@David-moonsite
@WiemSoued
Please upgrade to v2.3.2 which fixes the issue.

[David-moonsite]

Done, but now the top toolbar is gone ( download, zoom etc.... )