JNI错误（应用程序错误）：本地引用表溢出（最大值=512）

Question

我正在尝试使用自己的数据集运行LibSVMAndroidClassification Android项目。对于已经提供的数据集，它能够完美地工作，并且当我使用具有100行的csv时也可以正常工作（该数量不到原始大小的1%）。但是，当我尝试使用例如1000行的“Train CSV”时，就会出现此错误。我甚至尝试在Manifest.xml中设置android:largeHeap="true"，但仍然没有改善。

这是我的logcat dump。

10-31 17:49:06.745: E/dalvikvm(2008): JNI ERROR (app bug): local reference table overflow (max=512)
10-31 17:49:06.745: W/dalvikvm(2008): JNI local reference table (0x754057e0) dump:
10-31 17:49:06.745: W/dalvikvm(2008): Last 10 entries (of 512):
10-31 17:49:06.745: W/dalvikvm(2008): 511: 0x42d900b0 double
10-31 17:49:06.745: W/dalvikvm(2008): 510: 0x42a19698 int
10-31 17:49:06.745: W/dalvikvm(2008): 509: 0x42d8ff78 double
10-31 17:49:06.745: W/dalvikvm(2008): 508: 0x42a195f0 int
10-31 17:49:06.745: W/dalvikvm(2008): 507: 0x42d8fe40 double
10-31 17:49:06.745: W/dalvikvm(2008): 506: 0x42a19548 int
10-31 17:49:06.745: W/dalvikvm(2008): 505: 0x42d8fd08 double
10-31 17:49:06.745: W/dalvikvm(2008): 504: 0x42a194a0 int
10-31 17:49:06.745: W/dalvikvm(2008): 503: 0x42d8fbd0 double
10-31 17:49:06.745: W/dalvikvm(2008): 502: 0x42a193f8 int
10-31 17:49:06.745: W/dalvikvm(2008): Summary:
10-31 17:49:06.745: W/dalvikvm(2008): 5 of java.lang.Class (4 unique instances)
10-31 17:49:06.745: W/dalvikvm(2008): 3 of java.lang.String (3 unique instances)
10-31 17:49:06.745: W/dalvikvm(2008): 249 of int (249 unique instances)
10-31 17:49:06.745: W/dalvikvm(2008): 1 of int
10-31 17:49:06.745: W/dalvikvm(2008): 250 of double (250 unique instances)
10-31 17:49:06.745: W/dalvikvm(2008): 1 of java.lang.String
10-31 17:49:06.745: W/dalvikvm(2008): 1 of int[]
10-31 17:49:06.745: W/dalvikvm(2008): 1 of edu.sinica.citi.mac.android.actclassification.ActClassificationActivity
10-31 17:49:06.745: W/dalvikvm(2008): 1 of double[]
10-31 17:49:06.745: E/dalvikvm(2008): Failed adding to JNI local ref table (has 512 entries)
10-31 17:49:06.745: I/dalvikvm(2008): "main" prio=5 tid=1 RUNNABLE
10-31 17:49:06.745: I/dalvikvm(2008): | group="main" sCount=0 dsCount=0 obj=0x42027710 self=0x420115f0
10-31 17:49:06.745: I/dalvikvm(2008): | sysTid=2008 nice=0 sched=0/0 cgrp=apps handle=1074106620
10-31 17:49:06.745: I/dalvikvm(2008): | state=R schedstat=( 774483646 137982240 4930 ) utm=59 stm=18 core=1
10-31 17:49:06.745: I/dalvikvm(2008): at edu.sinica.citi.mac.android.actclassification.ActClassificationActivity.svmtrain(Native Method)
10-31 17:49:06.745: I/dalvikvm(2008): at edu.sinica.citi.mac.android.actclassification.ActClassificationActivity.train_csv(ActClassificationActivity.java:329)
10-31 17:49:06.745: I/dalvikvm(2008): at edu.sinica.citi.mac.android.actclassification.ActClassificationActivity$2.onClick(ActClassificationActivity.java:125)
10-31 17:49:06.745: I/dalvikvm(2008): at android.view.View.performClick(View.java:4249)
10-31 17:49:06.745: I/dalvikvm(2008): at android.view.View$PerformClick.run(View.java:17764)
10-31 17:49:06.745: I/dalvikvm(2008): at android.os.Handler.handleCallback(Handler.java:730)
10-31 17:49:06.745: I/dalvikvm(2008): at android.os.Handler.dispatchMessage(Handler.java:92)
10-31 17:49:06.745: I/dalvikvm(2008): at android.os.Looper.loop(Looper.java:137)
10-31 17:49:06.745: I/dalvikvm(2008): at android.app.ActivityThread.main(ActivityThread.java:5137)
10-31 17:49:06.745: I/dalvikvm(2008): at java.lang.reflect.Method.invokeNative(Native Method)
10-31 17:49:06.745: I/dalvikvm(2008): at java.lang.reflect.Method.invoke(Method.java:525)
10-31 17:49:06.745: I/dalvikvm(2008): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:752)
10-31 17:49:06.745: I/dalvikvm(2008): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:568)
10-31 17:49:06.745: I/dalvikvm(2008): at miui.dexspy.DexspyInstaller.main(DexspyInstaller.java:171)
10-31 17:49:06.745: I/dalvikvm(2008): at dalvik.system.NativeStart.main(Native Method)
10-31 17:49:06.745: E/dalvikvm(2008): VM aborting
10-31 17:49:06.745: A/libc(2008): Fatal signal 11 (SIGSEGV) at 0xdeadd00d (code=1), thread 2008 (tclassification)

我已经搜索了很多，但仍然无法理解这背后的背景和原因。许多人在不同的情况下都遇到了相同的错误。有什么适当的指针可以指向解决方案吗？

提前感谢！

- Wahib Ul Haq

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通常问题是某个东西创建了本地引用但未删除它们（例如请参见 http://developer.android.com/training/articles/perf-jni.html#local_and_global_references ）。由于某些原因，你的本地引用表被 int 和 double 占满了。如果对象在循环中创建，则应使用 DeleteLocalRef 将其删除，因为该表直到控制返回该线程的 VM 才会被清空。 - fadden

是的，它有所帮助！使用DeleteLocalRef()后问题已经解决了，因为Release函数不够。 - Wahib Ul Haq

Answer 1

你最好使用DeleteLocalRef来删除以后不会再使用的本地引用。 例如：

for (int i = 0; i < 512; i++)
{
        jobject obj = env->GetObjectArrayElement(array, i);
        //your code here    
        env->DeleteLocalRef(obj);   
}

- zhuzhenlei