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我已經使用JNI，JNA，BridJ和JavaCPP多次重建我的Java/C++項目，並且每次遇到隨機（不可預知的）分段錯誤。我已經驗證了使用這個庫的pure-C++可執行文件永遠不會導致分段錯誤，並且在BridJ的情況下，通過顯式調用它將其縮小到Java的垃圾回收器。JNA/BridJ etc中的分段錯誤
一個想到的是，這些庫創建調用free或delete，當他們得到垃圾收集（通過finalize），而不是治療的指針是C++的回報作爲借用引用Java端指針的對象，因爲他們應該在這個應用程序。我已經嘗試了一個額外的測試（未在下面展示）：我將API中的每個指針都轉換爲int64_t（long，在Java中），並在C++中明確地轉換爲適當的類型。我仍然看到罕見的段錯誤。
所以我的問題是廣泛的：什麼可能導致這個問題？我會接受使用JNA或BridJ的答案，因爲我可以輕鬆地在這兩者之間切換。我想我錯過了一個根本性的問題，因爲這個問題在我嘗試過的所有庫中都非常普遍。
具體而言，這是我的JNA版本。我正在鏈接CERN ROOT庫。 RootTreeReader.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());
}
他們的Makefile
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();
}
};
}
和我稱之爲這樣的：
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")
它出現segfaults 很少有或沒有明確的垃圾收集器調用。 Bridjan版本的這段錯誤很少沒有和頻繁與顯式垃圾收集器調用。
JNA將只釋放它已經分配的內存，並且它在非常明確定義的位置執行（參見'Native.dispose（）'，它引用它們全部）。您可以選擇性地禁用這些處理方法中的每一種，以確定是否涉及其中的任何一種。 – technomage
你有我可以看看的JavaCPP版本嗎？ –
我試過JavaCPP 1.1，雖然上面的例子是JNA。 –