[llvm-dev] taskpool exhaustion in lld/wasm

Carlo Kok via llvm-dev llvm-dev at lists.llvm.org
Wed May 8 05:33:35 PDT 2019


It's a wasm testcase that ends up with a 1 mb executable; after 15 minutes I killed it, it doesn't do anything (note that it's waiting on a conditional variable in ALL threads)

On Wed, May 8, 2019, at 14:32, Brian Cain wrote:
> Are you sure it's not just taking "a long time"? If that build machine doesn't have enormous amounts of memory you could end up with a link phase that takes tons of time for projects like clang or chrome. 
> 
> Try linking a minimal case. If the bug you describe were there it should reproduce easily (maybe once you get up to enough object files or sections, whatever it's iterating over). 
> 
> On Wed, May 8, 2019, 7:25 AM Carlo Kok via llvm-dev <llvm-dev at lists.llvm.org> wrote:
>> On a 12" MacBook (2017) with 2 cores I get lld/wasm to be stuck in:
>> 
>> https://gist.githubusercontent.com/carlokok/1a14e7ed3dbbd54511e1f0b3a7d684ff/raw/19267560b584ca42cc66f44f508df5b34102d803/thread%2520for%2520waiting
>> 
>>  It seems the outer for loop exhausts the thread pool, and the inner ones trigger a new parallel for which never finishes because the pool is full. Is this a bug or am I missing something obvious?
>> 
>> 
>>  --
>>  Carlo Kok
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>> llvm-dev at lists.llvm.org
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