JNA/BridJ等故障的分割

Question

我多次使用JNI、JNA、BridJ和JavaCPP重新构建我的Java/C++项目，每次我遇到随机(不可预测的)分段错误。我已经验证了使用此库的纯C++可执行文件不会导致分段错误，在BridJ的情况下，通过显式调用它将其缩小为Java的垃圾收集器。

其中一个想法是，这些库正在创建Java端指针对象，当它们(通过free )收集垃圾时调用delete或finalize，而不是像在这个应用程序中那样将C++返回的指针当作借来的引用来处理。

但我尝试了一个额外的测试(如下所示)：我将API中的每个指针转换为int64_t (long in C++ )，并在C++中显式地转换为合适的类型。我仍然能看到罕见的节段断层。

所以我的问题很广泛:是什么导致了这个问题？我将使用JNA或BridJ接受答案，因为我可以轻松地在这两者之间切换。我想我忽略了一个根本性的问题，因为这个问题在我尝试过的所有库中都很普遍。

为了具体起见，这是我的JNA版本。我将链接到CERN根库。H是：

#ifndef ROOTTREEREADER_H
#define ROOTTREEREADER_H

#include <TFile.h>
#include <TTreeReader.h>
#include <TTreeReaderValue.h>
#include <TTreeReaderArray.h>

using namespace ROOT::Internal;

extern "C" {
  TFile *newFile(const char *fileLocation);
  TTreeReader *newReader(TFile *file, const char *treeLocation);
  bool readerNext(TTreeReader *reader);

  TTreeReaderValueBase *newValue_float(TTreeReader *reader, const char *name);

  float getValue_float(TTreeReaderValueBase *value);
}

#endif // ROOTTREEREADER_H

RootTreeReader.cpp是：

#include <string>

#include "RootTreeReader.h"

TFile *newFile(const char *fileLocation) {
  return TFile::Open(fileLocation);
}

TTreeReader *newReader(TFile *file, const char *treeLocation) {
  return new TTreeReader(treeLocation, file);
}

bool readerNext(TTreeReader *reader) {
  return reader->Next();
}

TTreeReaderValueBase *newValue_float(TTreeReader *reader, const char *name) {
  return new TTreeReaderValue<float>(*reader, name);
}

float getValue_float(TTreeReaderValueBase *value) {
  return *((float*)value->GetAddress());
}

他们的制造文件是

all: RootTreeReader.cpp
    mkdir -p ../../../target/native/linux-x86-64
    g++ RootTreeReader.cpp -o ../../../target/native/linux-x86-64/libRootTreeReader.so \
        -fPIC -shared \
        -Wl,--no-as-needed $(shell root-config --cflags --ldflags --libs) -lTreePlayer

JNAerator生成以下RootTreeReaderLibrary.java：

package org.dianahep.scaroot;
import com.sun.jna.Library;
import com.sun.jna.Native;
import com.sun.jna.NativeLibrary;
import com.sun.jna.Pointer;
import com.sun.jna.PointerType;
/**
 * JNA Wrapper for library <b>RootTreeReader</b><br>
 * This file was autogenerated by <a href="http://jnaerator.googlecode.com/">JNAerator</a>,<br>
 * a tool written by <a href="http://ochafik.com/">Olivier Chafik</a> that <a href="http://code.google.com/p/jnaerator/wiki/CreditsAndLicense">uses a few opensource projects.</a>.<br>
 * For help, please visit <a href="http://nativelibs4java.googlecode.com/">NativeLibs4Java</a> , <a href="http://rococoa.dev.java.net/">Rococoa</a>, or <a href="http://jna.dev.java.net/">JNA</a>.
 */
public interface RootTreeReaderLibrary extends Library {
    public static final String JNA_LIBRARY_NAME = "RootTreeReader";
    public static final NativeLibrary JNA_NATIVE_LIB = NativeLibrary.getInstance(RootTreeReaderLibrary.JNA_LIBRARY_NAME);
    public static final RootTreeReaderLibrary INSTANCE = (RootTreeReaderLibrary)Native.loadLibrary(RootTreeReaderLibrary.JNA_LIBRARY_NAME, RootTreeReaderLibrary.class);
    /**
     * Original signature : <code>TFile* newFile(const char*)</code><br>
     * <i>native declaration : src/main/cpp/RootTreeReader.h:5</i><br>
     * @deprecated use the safer methods {@link #newFile(java.lang.String)} and {@link #newFile(com.sun.jna.Pointer)} instead
     */
    @Deprecated 
    RootTreeReaderLibrary.TFile newFile(Pointer fileLocation);
    /**
     * Original signature : <code>TFile* newFile(const char*)</code><br>
     * <i>native declaration : src/main/cpp/RootTreeReader.h:5</i>
     */
    RootTreeReaderLibrary.TFile newFile(String fileLocation);
    /**
     * Original signature : <code>TTreeReader* newReader(TFile*, const char*)</code><br>
     * <i>native declaration : src/main/cpp/RootTreeReader.h:6</i><br>
     * @deprecated use the safer methods {@link #newReader(org.dianahep.scaroot.RootTreeReaderLibrary.TFile, java.lang.String)} and {@link #newReader(org.dianahep.scaroot.RootTreeReaderLibrary.TFile, com.sun.jna.Pointer)} instead
     */
    @Deprecated 
    RootTreeReaderLibrary.TTreeReader newReader(RootTreeReaderLibrary.TFile file, Pointer treeLocation);
    /**
     * Original signature : <code>TTreeReader* newReader(TFile*, const char*)</code><br>
     * <i>native declaration : src/main/cpp/RootTreeReader.h:6</i>
     */
    RootTreeReaderLibrary.TTreeReader newReader(RootTreeReaderLibrary.TFile file, String treeLocation);
    /**
     * Original signature : <code>bool readerNext(TTreeReader*)</code><br>
     * <i>native declaration : src/main/cpp/RootTreeReader.h:7</i>
     */
    byte readerNext(RootTreeReaderLibrary.TTreeReader reader);
    /**
     * Original signature : <code>TTreeReaderValueBase* newValue_float(TTreeReader*, const char*)</code><br>
     * <i>native declaration : src/main/cpp/RootTreeReader.h:9</i><br>
     * @deprecated use the safer methods {@link #newValue_float(org.dianahep.scaroot.RootTreeReaderLibrary.TTreeReader, java.lang.String)} and {@link #newValue_float(org.dianahep.scaroot.RootTreeReaderLibrary.TTreeReader, com.sun.jna.Pointer)} instead
     */
    @Deprecated 
    RootTreeReaderLibrary.TTreeReaderValueBase newValue_float(RootTreeReaderLibrary.TTreeReader reader, Pointer name);
    /**
     * Original signature : <code>TTreeReaderValueBase* newValue_float(TTreeReader*, const char*)</code><br>
     * <i>native declaration : src/main/cpp/RootTreeReader.h:9</i>
     */
    RootTreeReaderLibrary.TTreeReaderValueBase newValue_float(RootTreeReaderLibrary.TTreeReader reader, String name);
    /**
     * Original signature : <code>float getValue_float(TTreeReaderValueBase*)</code><br>
     * <i>native declaration : src/main/cpp/RootTreeReader.h:11</i>
     */
    float getValue_float(RootTreeReaderLibrary.TTreeReaderValueBase value);
    public static class TFile extends PointerType {
        public TFile(Pointer address) {
            super(address);
        }
        public TFile() {
            super();
        }
    };
    public static class TTreeReader extends PointerType {
        public TTreeReader(Pointer address) {
            super(address);
        }
        public TTreeReader() {
            super();
        }
    };
    public static class TTreeReaderValueBase extends PointerType {
        public TTreeReaderValueBase(Pointer address) {
            super(address);
        }
        public TTreeReaderValueBase() {
            super();
        }
    };
}

我这样叫它：

Native.setProtected(true)
println("Native.isProtected", Native.isProtected)   // it's true on Linux; I've tried this with and without

val lib = RootTreeReaderLibrary.INSTANCE

println("one")
val file = lib.newFile("TrackResonanceNtuple.root")
println("two")
val reader = lib.newReader(file, "TrackResonanceNtuple/twoMuon")
println("three")
val mass = lib.newValue_float(reader, "mass_mumu")
println("four")
var counter = 0
while (lib.readerNext(reader) > 0) {
  val num = lib.getValue_float(mass)
  println(num)
  counter += 1
  // if (counter % 1000 == 0) {
  //   println("gc start")
  //   System.gc()
  //   println("gc end")
  // }
}
println("five")

它的分段错误很少有显式的垃圾收集器调用或不存在。这个分段错误的BridJ版本很少没有并且经常使用显式的垃圾收集器调用。

Answer 1

快速解决办法：

export LD_PRELOAD=/path/to/libjsig.so

问题是CERN根试图为与JDK相同的信号安装处理程序。甲骨文建议预加载libjsig.so，它提供了一个“信号链接工具”，以解决以下问题：

https://docs.oracle.com/javase/6/docs/technotes/guides/vm/signal-chaining.html

编辑吉姆：

对于根框架，可以通过调用

gSystem->ResetSignals();

讨论可以在根留言板上找到：https://root.cern.ch/phpBB3/viewtopic.php?t=8231