I’ve blogged about the subject of GWT JVM crashes far too much (here and here).  This is, I hope, the final word on the subject.  I spent some time disassembling the Google Eclipse plugin (did I agree not to do that in one of the EULAs? ) and discovered that they are launching the JVM without using the Eclipse infrastructure.  This means that the JVM arguments are effectively hardcoded, except in one case where -startOnFirstThread is passed for OSX clients.  For those interested, the buggy classes of note are GWTDeploymentParticipant and LaunchUtils.

I posted a note on the contributor’s list and received a response from a Googler suggesting that I wrap my Java executable in a shell script.  Not one to shy away from wrapping system executables with scripts, I decided to give it a shot tonight.  My first shell script attempt was a disaster (dear lazyweb: how can you get bash to respect quoted spaces when using $@?), so I gave it a whack in Python.

This is tested and somewhat guaranteed to work for JVM 1.6 under OSX:

cd /System/Library/Frameworks/JavaVM.framework/Versions/1.6.0/Home/bin
sudo mv java java_wrapped
sudo nano java

And the script:

#!/usr/bin/env python
import sys
import os

print sys.argv
cmd = os.path.dirname(sys.argv[0]) + '/java_wrapped'

args = ['',
        '-XX:CompileCommand=exclude,org/eclipse/core/internal/dtree/DataTreeNode,forwardDeltaWith',
        '-XX:CompileCommand=exclude,org/eclipse/jdt/internal/compiler/lookup/ParameterizedTypeBinding,<init>',
        '-XX:CompileCommand=exclude,org/eclipse/jdt/internal/compiler/lookup/ParameterizedMethodBinding,<init>']

args.extend(sys.argv[1:])

print cmd
print args
print ""

os.execv(cmd, args)

If you have any suggestions on how to improve my Python, I’d be glad to hear them in the comments.

UPDATE: Thanks to Vitali, I got a bash script working as well:

#!/bin/bash
`dirname $0`/java_wrapped \
        "-XX:CompileCommand=exclude,org/eclipse/core/internal/dtree/DataTreeNode,forwardDeltaWith" \
        "-XX:CompileCommand=exclude,org/eclipse/jdt/internal/compiler/lookup/ParameterizedTypeBinding,<init>" \
        "-XX:CompileCommand=exclude,org/eclipse/jdt/internal/compiler/lookup/ParameterizedMethodBinding,<init>" \
        "$@"

UPDATE, Apr 19 2009: This does not fix all compiler crashes in Eclipse.  This is only useful for the compiler crashes where an Eclipse JVM configuration is used.  Please see my later blog post for a better fix and disregard this information.

This is the same error I hit before (see my earlier post), but it happens in Eclipse during the “deploy to AppEngine” phase.  You’ll see it if you’ve got a project configured with a 1.6 JVM on the build path (even if your .class compatibility is set to 1.5).  It’s not obvious how to fix this at first glance – I had to dig around to find the options that Eclipse passes to the JVM.

The solution

You can fix it by adding the same compiler workarounds we explored before to your JVM default arguments.  IMPORTANT NOTE: Add the args to all of your 1.6 level installed JVMs.  I’ve found that Eclipse doesn’t always choose the selected one if there’s an equivalent also installed (ie: it may use your ’1.6′ JVM if you have ’1.6.0′ selected).

-XX:CompileCommand=exclude,org/eclipse/core/internal/dtree/DataTreeNode,forwardDeltaWith -XX:CompileCommand=exclude,org/eclipse/jdt/internal/compiler/lookup/ParameterizedTypeBinding,<init> -XX:CompileCommand=exclude,org/eclipse/jdt/internal/compiler/lookup/ParameterizedMethodBinding,<init>

Add them to your JVMs under Preferences > Java > Installed JREs by clicking the edit button and filling out “Default VM Arguments”:

An example of where to place the arguments