Friday, September 14, 2018

Re: Why the GWT complier used so much memory?

To your point, regarding tuning the localWorkers parameter, I get significant speedup going from the default of 4 localWorkers down to 2. (i5-4460 Desktop CPU, 500 GB SSD and 32 GB of RAM). It doesn't matter what I set the heap limit to, the compilation appears to be memory bandwidth limited, or perhaps GC bandwidth limited. 

My times are roughly 300 s for 4 workers, 90 s for 2 and 100 s for 1. When compiling with 4 local workers, my system will lock up for a second here and there during compilation, the mouse will freeze, other applications will jitter. The system-wide jitter strongly suggests memory bandwidth saturation and poor cache performance on the part of the GWT compiler. I get no jitter with 2 localWorkers. 

My project code base is about 250 k lines, about 1/3-1/2 of that is front end GWT code. 

On Sunday, September 9, 2018 at 1:15:54 PM UTC-3, Jens wrote:

Are there someone working on the optimization of the GWT compiler, it is too slow for us


You can use -localWorkers parameter to adjust how many permutations should be compiled in parallel. The higher the number the more memory is needed. If you use -localWorkers 1 then permutations are compiled one after the other which requires the least amount of memory. You can also use -Xmx JVM parameter to limit the amount of heap used, although this might result in more garbage collects and thus longer compile times.

The only other option is to split a large app into smaller apps.

-- J.

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