RamUsageEstimator hangs with AOT compilation

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RamUsageEstimator hangs with AOT compilation

Cleber Muramoto
After generating a pre-compiled image lucene-core (8.3.0)  with jaotc (JDK
13.0.1), RamUsageEstimator class is never loaded - it fails to complete the
static initializer.

Steps to reproduce:

 1)Generate the image with

>jaotc --info --ignore-errors --jar ~/.m2/repository/org/apache/lucene/lucene-core/8.3.0/lucene-core-8.3.0.jar --output lucene-core.so

2)Create a simple test class to trigger class loading

 import java.io.IOException;

import java.nio.file.Path;
import java.nio.file.Paths;

import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.store.MMapDirectory;

public class TestAOT {

public static void main(String...args){
 run();
 System.out.println("Done");
 }
static void run(){
 try {
 var iw = new IndexWriter(MMapDirectory.open(Paths.get("dir")), new
IndexWriterConfig());
 iw.close();
 } catch (IOException e) {
 e.printStackTrace();
 }
 }
}

3)Run the class with the pre-compiled image

>java -XX:AOTLibrary=./lucene-core.so -XX:+PrintAOT  -cp ~/.m2/repository/org/apache/lucene/lucene-core/8.3.0/lucene-core-8.3.0.jar TestAOT.java

4)The program never completes. After inspecting it with jstack <pid> it
shows that it's stuck in line 195 of RamUsageEstimator

"main" #1 prio=5 os_prio=0 cpu=174827,04ms elapsed=173,91s
tid=0x00007fe984018800 nid=0x2daf runnable [0x00007fe98bc3c000]
  java.lang.Thread.State: RUNNABLE
    at
org.apache.lucene.util.RamUsageEstimator.<clinit>(RamUsageEstimator.java:195)

    at org.apache.lucene.util.ArrayUtil.<clinit>(ArrayUtil.java:31)
    at org.apache.lucene.index.IndexWriter.<clinit>(IndexWriter.java:276)
    at TestAOT.run(TestAOT.java:20)
    at TestAOT.main(TestAOT.java:14)
    at
jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(java.base@13.0.1/Native
Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(java.base@13.0.1/NativeMethodAccessorImpl.java:62)

    at
jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(java.base@13.0.1/DelegatingMethodAccessorImpl.java:43)

    at java.lang.reflect.Method.invoke(java.base@13.0.1/Method.java:567)
    at com.sun.tools.javac.launcher.Main.execute(jdk.compiler@13.0.1/Main.java:415)

    at com.sun.tools.javac.launcher.Main.run(jdk.compiler@13.0.1/Main.java:192)

    at com.sun.tools.javac.launcher.Main.main(jdk.compiler@13.0.1
/Main.java:132)

My guess is that the AOT compiler aggressive optimizations like
inlining/scalar replacing calls to Long.valueOf, are working against the
code's desired semantics.

Perhaps the logic to determine LONG_CACHE_[MIN/MAX]_VALUE could be
conditioned to VM version/vendor in Constants class. From [Open|Oracle]JDK
7 onwards (don't know about older versions) Long cache has a fixed range of
[-128,127], so there's no need to loop until a non-cached boxed value shows
up.

I know this compiler bug isn't Lucene's fault and as a workaround one could
use --compile-for-tiered or exclude RamUsageEstimator's methods from jaotc,
however, it would be nice to have a faster, allocation/loop-free
initializer for RamUsageEstimator nevertheless.

Cheers
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Re: RamUsageEstimator hangs with AOT compilation

Dawid Weiss-2
Thank you - I filed an issue for this, we will investigate.
https://issues.apache.org/jira/browse/LUCENE-9117

Dawid

On Mon, Jan 6, 2020 at 11:39 PM Cleber Muramoto
<[hidden email]> wrote:

>
> After generating a pre-compiled image lucene-core (8.3.0)  with jaotc (JDK
> 13.0.1), RamUsageEstimator class is never loaded - it fails to complete the
> static initializer.
>
> Steps to reproduce:
>
>  1)Generate the image with
>
> >jaotc --info --ignore-errors --jar ~/.m2/repository/org/apache/lucene/lucene-core/8.3.0/lucene-core-8.3.0.jar --output lucene-core.so
>
> 2)Create a simple test class to trigger class loading
>
>  import java.io.IOException;
>
> import java.nio.file.Path;
> import java.nio.file.Paths;
>
> import org.apache.lucene.index.IndexWriter;
> import org.apache.lucene.index.IndexWriterConfig;
> import org.apache.lucene.store.MMapDirectory;
>
> public class TestAOT {
>
> public static void main(String...args){
>  run();
>  System.out.println("Done");
>  }
> static void run(){
>  try {
>  var iw = new IndexWriter(MMapDirectory.open(Paths.get("dir")), new
> IndexWriterConfig());
>  iw.close();
>  } catch (IOException e) {
>  e.printStackTrace();
>  }
>  }
> }
>
> 3)Run the class with the pre-compiled image
>
> >java -XX:AOTLibrary=./lucene-core.so -XX:+PrintAOT  -cp ~/.m2/repository/org/apache/lucene/lucene-core/8.3.0/lucene-core-8.3.0.jar TestAOT.java
>
> 4)The program never completes. After inspecting it with jstack <pid> it
> shows that it's stuck in line 195 of RamUsageEstimator
>
> "main" #1 prio=5 os_prio=0 cpu=174827,04ms elapsed=173,91s
> tid=0x00007fe984018800 nid=0x2daf runnable [0x00007fe98bc3c000]
>   java.lang.Thread.State: RUNNABLE
>     at
> org.apache.lucene.util.RamUsageEstimator.<clinit>(RamUsageEstimator.java:195)
>
>     at org.apache.lucene.util.ArrayUtil.<clinit>(ArrayUtil.java:31)
>     at org.apache.lucene.index.IndexWriter.<clinit>(IndexWriter.java:276)
>     at TestAOT.run(TestAOT.java:20)
>     at TestAOT.main(TestAOT.java:14)
>     at
> jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(java.base@13.0.1/Native
> Method)
>     at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(java.base@13.0.1/NativeMethodAccessorImpl.java:62)
>
>     at
> jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(java.base@13.0.1/DelegatingMethodAccessorImpl.java:43)
>
>     at java.lang.reflect.Method.invoke(java.base@13.0.1/Method.java:567)
>     at com.sun.tools.javac.launcher.Main.execute(jdk.compiler@13.0.1/Main.java:415)
>
>     at com.sun.tools.javac.launcher.Main.run(jdk.compiler@13.0.1/Main.java:192)
>
>     at com.sun.tools.javac.launcher.Main.main(jdk.compiler@13.0.1
> /Main.java:132)
>
> My guess is that the AOT compiler aggressive optimizations like
> inlining/scalar replacing calls to Long.valueOf, are working against the
> code's desired semantics.
>
> Perhaps the logic to determine LONG_CACHE_[MIN/MAX]_VALUE could be
> conditioned to VM version/vendor in Constants class. From [Open|Oracle]JDK
> 7 onwards (don't know about older versions) Long cache has a fixed range of
> [-128,127], so there's no need to loop until a non-cached boxed value shows
> up.
>
> I know this compiler bug isn't Lucene's fault and as a workaround one could
> use --compile-for-tiered or exclude RamUsageEstimator's methods from jaotc,
> however, it would be nice to have a faster, allocation/loop-free
> initializer for RamUsageEstimator nevertheless.
>
> Cheers

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