PsiBuilder.advance & ProcessCanceledException

This is interesting - I see this thrown a lot during symbol resolution, as well. I can see it mostly when debugging. Although it seems to retry, I'm not sure why this process should be being canceled?

Are catching it? You should rethrow it so your thread dies properly. It is a normal exception that kills jobs spun up by the daemon processing.

It is thrown for example when you are parsing a document and the document is changed - your parse is invalid and needs to be restarted.

Here's the code I have in my parser:

    
@NotNull
    @Override
    public ASTNode parse(IElementType root, PsiBuilder builder) {

        final LuaPsiBuilder psiBuilder = new LuaPsiBuilder(builder);
        try {
            final PsiBuilder.Marker rootMarker = psiBuilder.mark();

            String name = "todo:name";
            source = name;
            KahluaParser lexstate = new KahluaParser(z, 0, source);
            FuncState funcstate = new FuncState(lexstate);

            /* main func. is always vararg */
            funcstate.isVararg = FuncState.VARARG_ISVARARG;
            funcstate.f.name = name;

            lexstate.builder = psiBuilder;
            lexstate.t = psiBuilder.getTokenType();
            lexstate.chunk();
            int pos = psiBuilder.getCurrentOffset();
            PsiBuilder.Marker mark  = psiBuilder.mark();
            while (!psiBuilder.eof())
                    psiBuilder.advanceLexer();

            if (psiBuilder.getCurrentOffset()>pos)
                mark.error("Unparsed code");
            else
                mark.drop();

            lexstate.close_func();

            FuncState._assert(funcstate.prev == null);
            FuncState._assert(funcstate.f.numUpvalues == 0);
            FuncState._assert(lexstate.fs == null);

            if (root != null)
                rootMarker.done(root);
        } catch (ProcessCanceledException e) {
            throw e;
        } catch (Exception e) {
            throw new PluginException("Exception During Parse At Offset: "+ builder.getCurrentOffset() + "\n\n" + builder.getOriginalText(), e, PluginId.getId("Lua"));
        }

You can add -Didea.ProcessCanceledException=disabled to avoid that for
debugging.
The exception indeed is thrown for performance reasons and it should be
rethrown

On 2/16/2012 12:59 AM, wallaby.pouch wrote:

Hi,
I'm debugging a nasty unbalanced PsiMarker problem in the BashSupport plugin.

>

The unbalanced marker seems to be caused by an ProcessCanceledException exception thrown in PsiBuilder.advance.

>

Code like:
//create marker
//advance builder
marker.done(...)

>

will leave an open marker if advance() throws an exceptions.

>

PsiBuilderImpl.advance calls ProgressIndicatorProvider.checkCanceled() which can throw a ProcessCanceledException .

>

Under which circumstances is the exception thrown?

>

Is there any way to work around this problem?

>

Developing for 11.x .

>

Thanks a lot,
Wallaby

>

---
Original message URL: http://devnet.jetbrains.net/message/5451875#5451875

Thanks a lot for all the replies.

I did not catch the exception but it seems to be caused by code like this (in the PsiParser implementation):

marker = builder.mark()
try {
//parsing which may cause a ProcessCanceledException exception
} finally {
     marker.done(root);
}

The finally block is called even if the exception was thrown and at this point the builder seems to be in an unusable state.

I removed the finally block and the problem seems to be fixed now.

Thanks!

Wallaby