so… I should set my optimize to level 8 or less as a work around?
This also impacts PRETTY mode?
On 11/5/25 14:58, Colin Alworth wrote:
Thanks for calling this out - it has been reported as
https://github.com/gwtproject/gwt/issues/9840 (and earlier), and as
time permits I've spent some effort trying to better understand it and
fix it. TL;DR: The code here is harder to read than usual due to some
questionable variable naming choices, but seems rooted in an attempt
to optimize by not running all of the JsInliner on the entire program,
resulting in missing cases like this. I have a patch that appears to
fix it (and makes sense logically), and is just missing some tests to
be sure.
Part of the problem here for code that never converges is that the
compiler's "optimization level" tracker believes that "9" is the
largest numbers can get - when counting compiler passes. That is, if
you ask for the max optimization level, that value is "9", and if
after 9 passes the compiler hasn't converged, it will keep going. Some
quick testing suggests that 8-11 passes seems "pretty good as a max",
but I think this means the max should have been 99 (or higher) so that
at some point it actually gives up. No error is required here, just
"stop, this is pointless" - and likewise, no timeout.
There's technically another heuristic that the Java optimization loop
uses, checking if the number of nodes changed/removed is higher than
the required baseline rate:
float nodeChangeRate = stats.getNumMods() / (float) lastNodeCount;
float sizeChangeRate = (lastNodeCount - nodeCount) / (float)
lastNodeCount;
if (nodeChangeRate <= minChangeRate && sizeChangeRate <=
minChangeRate) {
break;
}
https://github.com/gwtproject/gwt/blob/552c72eaa555a521d2e242d277273217704c1ed7/dev/core/src/com/google/gwt/dev/jjs/JavaToJavaScriptCompiler.java#L1440-L1444
Unfortunately, once you've hit "9" as your optimization level, this is
fixed at "any change at all is good, keep going".
Further, even if we did have a slightly higher baseline rate
configured, the JS optimization loop only counts passes, not change rate:
if ((optimizationLevel < OptionOptimize.OPTIMIZE_LEVEL_MAX &&
counter > optimizationLevel)
|| !stats.didChange()) {
break;
}
https://github.com/gwtproject/gwt/blob/552c72eaa555a521d2e242d277273217704c1ed7/dev/core/src/com/google/gwt/dev/jjs/JavaToJavaScriptCompiler.java#L1004-L1007
And as it happens, that's where the bug is, in optimizing JS, not Java.
I've mused about adding a timeout option also, something like
"whatever you've gotten done in 30s is good enough, give up", but the
use case is a little weird - impatient devs who still want optimized
code, and nondeterministic (but still correct) output? Seems like a
recipe for frustration, but that's just my two cents.
As part of this and some other optimization pass enhancements, I'm
hoping to improve both how we collect metrics on the compiler
performance and how we debug the work it actually does, so that we can
more confidently make changes in this area, or at least make it easier
for users to report what they're seeing without sharing their entire
codebase.
On Wednesday, November 5, 2025 at 1:27:03 PM UTC-6 Michael Joyner wrote:
Hello all,
I had a recursive setter get created while switching a field’s name.
I ended up with:
|public void setSearchTerm(String searchTerm) {
setSearchTerm(searchTerm); } |
And the gwtCompile just stops and sits there… (I presume after a
very very very very long time it would error out?)
Is this a known bug? Feature?
-Mike
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