Accepting jdwp connection early enough to debug Graal startup with -Xcomp

Doug Simon doug.simon at
Wed Aug 28 13:33:43 UTC 2019

> On 28 Aug 2019, at 15:08, Alan Bateman <Alan.Bateman at> wrote:
> On 28/08/2019 13:35, Doug Simon wrote:
>> Alan,
>> Thanks a lot for the input.
>> My only further comment is that with libgraal, the whole JDWP question is irrelevant as Graal will not be running as Java code (from HotSpot’s perspective).
> Sure but my point is that it might be possible to queue compilations earlier in the startup when the compiler is precompiled. That is, I thought Gary's mail was about debugging the compiler which I assume will need a solution when compiled to libgraal.

The only solution available then is to use a native debugger (native-image compiled code does not support JVMTI).

In terms of developing/debugging Graal, the working assumption is that compiler errors should mostly be debuggable in jargraal mode. There’s also an effort underway to add compilation replay support to Graal to improve debugging support where compiler errors are only occurring in libgraal mode.


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