file descriptors、java.lang.OutOfMemoryError以及open failed: EMFILE

开发过程中出现了运行时异常java.lang.RuntimeException: Could not read input channel file descriptors from parcel.接着又报java.lang.OutOfMemoryError: Could not allocate JNI Env的异常，应用奔溃打不开。

AndroidRuntime:java.lang.RuntimeException: Could not read input channel file descriptors from parcel.
at android.view.InputChannel.nativeReadFromParcel(Native Method)
at android.view.InputChannel.readFromParcel(InputChannel.java:148)
at android.view.InputChannel$1.createFromParcel(InputChannel.java:39)
at android.view.InputChannel$1.createFromParcel(InputChannel.java:37)
at com.android.internal.view.InputBindResult.(InputBindResult.java:68)
at com.android.internal.view.InputBindResult$1.createFromParcel(InputBindResult.java:112)
at com.android.internal.view.InputBindResult$1.createFromParcel(InputBindResult.java:111)
at com.android.internal.view.IInputMethodManager$Stub$Proxy.windowGainedFocus(IInputMethodManager.java:757)
at android.view.inputmethod.InputMethodManager.startInputInner(InputMethodManager.java:1279)
at android.view.inputmethod.InputMethodManager.onPostWindowFocus(InputMethodManager.java:1503)
at android.view.ViewRootImpl$ViewRootHandler.handleMessage(ViewRootImpl.java:3846)
at android.os.Handler.dispatchMessage(Handler.java:111)
at android.os.Looper.loop(Looper.java:207)
at android.app.ActivityThread.main(ActivityThread.java:5817)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:852)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:742)

先后出现异常，出现内存溢出的异常。

AndroidRuntime: java.lang.OutOfMemoryError: Could not allocate JNI Env
at java.lang.Thread.nativeCreate(Native Method)
at java.lang.Thread.start(Thread.java:1063)
at com.example.carvideo.CameraPreview.initCamera(CameraPreview.java:120)
at com.example.carvideo.CameraPreview.-wrap0(CameraPreview.java)
at com.example.carvideo.CameraPreview$BackgroundHandle.handleMessage(CameraPreview.java:388)
at android.os.Handler.dispatchMessage(Handler.java:111)
at android.os.Looper.loop(Looper.java:207)
at android.os.HandlerThread.run(HandlerThread.java:61)

回看日志发现捕获的异常 java.io.FileNotFoundException/ proc/1603/cmdline: open failed: EMFILE (Too many open files)，这里明显打开过多文件导致内存异常。

System.err: java.io.FileNotFoundException: /proc/1603/cmdline: open failed: EMFILE (Too many open files)
System.err: at libcore.io.IoBridge.open(IoBridge.java:487)
System.err: at java.io.FileInputStream.(FileInputStream.java:76)
System.err: at java.io.FileInputStream.(FileInputStream.java:103)
System.err: at android.hardware.Camera.isRestricted(Camera.java:2991)
System.err: at android.hardware.Camera.getParameters(Camera.java:3087)
System.err: at com.example.carvideo.CameraPreview.initCamera(CameraPreview.java:100)
System.err: at com.example.carvideo.CameraPreview.-wrap0(CameraPreview.java)
System.err: at com.example.carvideo.CameraPreview$BackgroundHandle.handleMessage(CameraPreview.java:388)
System.err: at android.os.Handler.dispatchMessage(Handler.java:111)
System.err: at android.os.Looper.loop(Looper.java:207)
System.err: at android.os.HandlerThread.run(HandlerThread.java:61)
System.err: Caused by: android.system.ErrnoException: open failed: EMFILE (Too many open files)
System.err: at libcore.io.Posix.open(Native Method)
System.err: at libcore.io.BlockGuardOs.open(BlockGuardOs.java:186)
System.err: at libcore.io.IoBridge.open(IoBridge.java:473)
System.err: … 10 more

查看代码每次初始化时 *** 作文件节点时的Cusor未及时关闭close导致内存溢出。对于内核而言，所有打开的文件都是通过文件描述符引用。文件描述符的 *** 作范围有限制，不同的系统限制最大值是不同的，每个进程的文件描述符的有硬限制，超过限制则报如上错误。