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[mkgmap-dev] Splitter Java Heap

From Felix Herwegh mlmmduk at herwegh.de on Wed Mar 20 19:39:55 GMT 2024

Hi Gerd,


 From the java --version output (in the first mail) I assumed already 
beeing on a 64-bit JRE and, following your advice, set -Xmx4G. Bingo, 
succes in the first pass on the weak machine.

    /JVM Memory Info: Current 3990MB (1967MB used, 2023MB free) Max 4096MB/

I still wonder how to read the figures though, as for the former 
successfull passes only about 1300 MB where reported used. and every 
pass reportedly still had free memory, although "current" was = "max." 
on the fails.

So, how to figure out an appropriate allocation? By map and/or machine?

Altough reading up on splitters documentation I seem to have been 
derailled by the description for  --max-areas parameter

    /Higher numbers ... require more memory/

    /Note that the first stage of the processing has a fixed memory
    overhead regardless of what this is set to so if you are running out
    of memory before the areas.list file is generated, you need to
    either increase your -Xmx value.../

Therefore I fiddled with max-areas, but didn't try to use -Xmx myself.

But, I now see, why --max-areas didn't change a thing in my case, as 
-for the map in question- I get:

    /Processing 293 areas in a single pass

// Felix

On 20.03.24 15:16, Gerd Petermann wrote:
> Hi Felix,
> I guess your laptop is running a 32-bit JRE, so your first step should be to install a 64 bit version if you have a 64 bit OS.
> With this done you can increase the max heap to e.g. 4GB with something like
> java -Xmx4G -jar splitter.jar ....
> If you cannot increase the memory you can switch of the --keep-complete option (with the corresponding disadvantages)
> Gerd
> ________________________________________
> Von: mkgmap-dev<mkgmap-dev-bounces at lists.mkgmap.org.uk>  im Auftrag von Felix Herwegh<mlmmduk at herwegh.de>
> Gesendet: Mittwoch, 20. März 2024 15:03
> An:mkgmap-dev at lists.mkgmap.org.uk
> Betreff: [mkgmap-dev] Splitter Java Heap
> Hi,
> switching to my Ultrabook (6 GB) while travelling I recently faced some kind of borderline condition with splitter. On the first run it throws "OutOfMemoryError: Java heap space", on closely subsequent runs without any modifications it does not. Repeating the task after some delay fails again. I guess, there might be some self-optimization involved for this.
> fail:
> ...
> 40.000.000 ways parsed... id=888262666
>    Number of stored tile combinations in multiTileDictionary: 4.525
> 41.000.000 ways parsed... id=929920953
> Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
>      at uk.me.parabola.splitter.tools.SparseLong2IntMap$ChunkMem.<init>(SparseLong2IntMap.java:189)
>      at uk.me.parabola.splitter.tools.SparseLong2IntMap.saveCurrentChunk(SparseLong2IntMap.java:627)
>      at uk.me.parabola.splitter.tools.SparseLong2IntMap.replaceCurrentChunk(SparseLong2IntMap.java:886)
>      at uk.me.parabola.splitter.tools.SparseLong2IntMap.put(SparseLong2IntMap.java:691)
>      at uk.me.parabola.splitter.SplitProcessor.processWay(SplitProcessor.java:149)
>      at uk.me.parabola.splitter.AbstractMapProcessor.consume(AbstractMapProcessor.java:84)
>      at uk.me.parabola.splitter.OSMFileHandler.execute(OSMFileHandler.java:157)
>      at uk.me.parabola.splitter.Main.writeTiles(Main.java:542)
>      at uk.me.parabola.splitter.Main.start(Main.java:132)
>      at uk.me.parabola.splitter.Main.main(Main.java:81)
> Elapsed time: 8m 0s   Memory: Current 1466MB (1339MB used, 127MB free) Max 1466MB
> success:
> ...
> 48.000.000 ways parsed... id=1262369277
> Writing relations Tue Mar 19 10:50:36 CET 2024
> 100.000 relations parsed... id=1783690
> 200.000 relations parsed... id=4148045
> 300.000 relations parsed... id=7895430
> 400.000 relations parsed... id=11681672
> 500.000 relations parsed... id=15581604
> coord Map: 312.851.126 stored long/int pairs require ca. 3 bytes per pair. 14.225.657 chunks are used, the avg. number of values in one 64-chunk is 21.
> coord Map details: ~852 MB, including 88 array(s) with 8 MB
> way Map: 48.015.926 stored long/int pairs require ca. 3 bytes per pair. 3.974.651 chunks are used, the avg. number of values in one 64-chunk is 12.
> way Map details: ~123 MB, including 10 array(s) with 8 MB
>    JVM Memory Info: Current 1466MB (1357MB used, 109MB free) Max 1466MB
> Full Node tests:  62.230.523
> Quick Node tests: 282.354.912
> Thread worker-2 has finished
> ...
> My main machine has 24 GB of main memory, and runs troublefree using the following memory allocation on the same task:
> JVM Memory Info: Current 3342MB (2378MB used, 964MB free) Max 6000MB
> Splitter 653 so far is involved without explicit memory allocation (java -jar .../splitter-latest/splitter.jar ...), using
> java --version
> openjdk 11.0.22 2024-01-16
> OpenJDK Runtime Environment (build 11.0.22+7-post-Debian-1deb10u1)
> OpenJDK 64-Bit Server VM (build 11.0.22+7-post-Debian-1deb10u1, mixed mode, sharing)
> Following up on splitter tuning hints (areas.list gets generated in each case) I reduced --max-areas= from 4096 to 2048 to 1024, but to no avail (not even significantly on the runtimes), once I figured out the effect above. It fails on all first runs and succeeds on all shortly following next ones.
> Unfortunately its not possible to increase main hardware memory on the small machine, but system tools report only about 2...3 GB being used anyway.
> Is it possible to tweak Java to overcome the problem without hurting the maps, preferably by machine, to be able to run identical scripts? Some pointers would be appreciated, also on how to monitor the Java memory situation.
> Thanks, Felix
> _______________________________________________
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> mkgmap-dev at lists.mkgmap.org.uk
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