java - 如何在应用程序崩溃之前捕获 OutOfMemoryError？

Question

我编写了一个 Android 应用程序，在其中实现了一个求解器。求解器分配大量内存。对于简单的问题，它可以毫无问题地工作。但当问题变得更加复杂时，我收到错误“2164 字节分配内存不足”并且应用程序崩溃。

我尝试使用

try {
        solver();
}
catch (Exception e) {
}

但这并不能阻止应用程序崩溃。

我还在 AndroidManifest.xml 中尝试了“android:largeHeap="true"。

有没有办法获得更多内存或在内存满之前停止求解器？

04-18 11:39:10.953: D/dalvikvm(979): GC_FOR_ALLOC freed 25K, 5% free 31446K/32768K, paused 363ms, total 363ms
04-18 11:39:10.953: I/dalvikvm-heap(979): Forcing collection of SoftReferences for 93404-byte allocation
04-18 11:39:11.283: I/dalvikvm-heap(979): Clamp target GC heap from 32.832MB to 32.000MB
04-18 11:39:11.293: D/dalvikvm(979): GC_BEFORE_OOM freed <1K, 5% free 31445K/32768K, paused 331ms, total 332ms
04-18 11:39:11.293: E/dalvikvm-heap(979): Out of memory on a 93404-byte allocation.
04-18 11:39:11.293: I/dalvikvm(979): "AdWorker #1" prio=5 tid=11 RUNNABLE
04-18 11:39:11.293: I/dalvikvm(979):   | group="main" sCount=0 dsCount=0 obj=0xb48db908 self=0xb7ecf560
04-18 11:39:11.293: I/dalvikvm(979):   | sysTid=1015 nice=10 sched=0/0 cgrp=apps/bg_non_interactive handle=-1209206344
04-18 11:39:11.303: I/dalvikvm(979):   | state=R schedstat=( 2590000000 85040000000 791 ) utm=236 stm=23 core=0
04-18 11:39:11.303: I/dalvikvm(979):   at java.lang.AbstractStringBuilder.enlargeBuffer(AbstractStringBuilder.java:~94)
04-18 11:39:11.303: I/dalvikvm(979):   at java.lang.AbstractStringBuilder.append0(AbstractStringBuilder.java:162)
04-18 11:39:11.303: I/dalvikvm(979):   at java.lang.StringBuilder.append(StringBuilder.java:311)
04-18 11:39:11.313: I/dalvikvm(979):   at com.google.android.gms.internal.eo.a((null):-1)
04-18 11:39:11.313: I/dalvikvm(979):   at com.google.android.gms.internal.dx.a((null):-1)
04-18 11:39:11.313: I/dalvikvm(979):   at com.google.android.gms.internal.dx.a((null):-1)
04-18 11:39:11.313: I/dalvikvm(979):   at com.google.android.gms.internal.dx.b((null):-1)
04-18 11:39:11.313: I/dalvikvm(979):   at com.google.android.gms.internal.dq.a((null):-1)
04-18 11:39:11.313: I/dalvikvm(979):   at com.google.android.gms.internal.dq.bh((null):-1)
04-18 11:39:11.313: I/dalvikvm(979):   at com.google.android.gms.internal.em$1.run((null):-1)
04-18 11:39:11.313: I/dalvikvm(979):   at com.google.android.gms.internal.en$1.run((null):-1)
04-18 11:39:11.313: I/dalvikvm(979):   at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
04-18 11:39:11.313: I/dalvikvm(979):   at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
04-18 11:39:11.313: I/dalvikvm(979):   at java.lang.Thread.run(Thread.java:841)
04-18 11:39:11.333: I/Choreographer(979): Skipped 83 frames!  The application may be doing too much work on its main thread.
04-18 11:39:11.393: W/dalvikvm(979): threadid=11: thread exiting with uncaught exception (group=0xb3a7eba8)
04-18 11:39:11.873: I/dalvikvm-heap(979): Clamp target GC heap from 32.746MB to 32.000MB
04-18 11:39:11.883: D/dalvikvm(979): GC_FOR_ALLOC freed 132K, 5% free 31357K/32768K, paused 426ms, total 426ms
04-18 11:39:11.903: I/Choreographer(979): Skipped 44 frames!  The application may be doing too much work on its main thread.
04-18 11:39:12.613: I/dalvikvm-heap(979): Clamp target GC heap from 32.793MB to 32.000MB
04-18 11:39:12.633: D/dalvikvm(979): GC_FOR_ALLOC freed 163K, 5% free 31405K/32768K, paused 488ms, total 489ms
04-18 11:39:13.013: I/dalvikvm-heap(979): Clamp target GC heap from 32.796MB to 32.000MB
04-18 11:39:13.013: D/dalvikvm(979): GC_FOR_ALLOC freed 12K, 5% free 31409K/32768K, paused 374ms, total 374ms
04-18 11:39:13.013: I/dalvikvm-heap(979): Forcing collection of SoftReferences for 2162-byte allocation
04-18 11:39:13.373: I/dalvikvm-heap(979): Clamp target GC heap from 32.796MB to 32.000MB
04-18 11:39:13.373: D/dalvikvm(979): GC_BEFORE_OOM freed <1K, 5% free 31409K/32768K, paused 354ms, total 355ms
04-18 11:39:13.373: E/dalvikvm-heap(979): Out of memory on a 2162-byte allocation.
04-18 11:39:13.373: I/dalvikvm(979): "AdWorker #1" prio=5 tid=11 RUNNABLE
04-18 11:39:13.373: I/dalvikvm(979):   | group="main" sCount=0 dsCount=0 obj=0xb48db908 self=0xb7ecf560
04-18 11:39:13.373: I/dalvikvm(979):   | sysTid=1015 nice=10 sched=0/0 cgrp=apps/bg_non_interactive handle=-1209206344
04-18 11:39:13.383: I/dalvikvm(979):   | state=R schedstat=( 3560000000 85730000000 847 ) utm=331 stm=25 core=0
04-18 11:39:13.383: I/dalvikvm(979):   at java.lang.AbstractStringBuilder.enlargeBuffer(AbstractStringBuilder.java:~94)
04-18 11:39:13.383: I/dalvikvm(979):   at java.lang.AbstractStringBuilder.append0(AbstractStringBuilder.java:124)
04-18 11:39:13.383: I/dalvikvm(979):   at java.lang.StringBuffer.append(StringBuffer.java:278)
04-18 11:39:13.383: I/dalvikvm(979):   at java.io.StringWriter.write(StringWriter.java:123)
04-18 11:39:13.383: I/dalvikvm(979):   at com.android.internal.util.FastPrintWriter.flushLocked(FastPrintWriter.java:358)
04-18 11:39:13.383: I/dalvikvm(979):   at com.android.internal.util.FastPrintWriter.flush(FastPrintWriter.java:387)
04-18 11:39:13.383: I/dalvikvm(979):   at android.util.Log.getStackTraceString(Log.java:335)
04-18 11:39:13.383: I/dalvikvm(979):   at android.util.Slog.e(Slog.java:77)
04-18 11:39:13.383: I/dalvikvm(979):   at com.android.internal.os.RuntimeInit$UncaughtHandler.uncaughtException(RuntimeInit.java:80)
04-18 11:39:13.383: I/dalvikvm(979):   at java.lang.ThreadGroup.uncaughtException(ThreadGroup.java:693)
04-18 11:39:13.393: I/dalvikvm(979):   at java.lang.ThreadGroup.uncaughtException(ThreadGroup.java:690)
04-18 11:39:13.713: I/dalvikvm-heap(979): Clamp target GC heap from 32.799MB to 32.000MB
04-18 11:39:13.723: D/dalvikvm(979): GC_FOR_ALLOC freed 7K, 5% free 31412K/32768K, paused 327ms, total 327ms
04-18 11:39:13.723: I/dalvikvm-heap(979): Forcing collection of SoftReferences for 2164-byte allocation
04-18 11:39:14.063: I/dalvikvm-heap(979): Clamp target GC heap from 32.799MB to 32.000MB
04-18 11:39:14.063: D/dalvikvm(979): GC_BEFORE_OOM freed 0K, 5% free 31412K/32768K, paused 344ms, total 345ms
04-18 11:39:14.073: E/dalvikvm-heap(979): Out of memory on a 2164-byte allocation.
04-18 11:39:14.073: I/dalvikvm(979): "AdWorker #1" prio=5 tid=11 RUNNABLE
04-18 11:39:14.073: I/dalvikvm(979):   | group="main" sCount=0 dsCount=0 obj=0xb48db908 self=0xb7ecf560
04-18 11:39:14.073: I/dalvikvm(979):   | sysTid=1015 nice=10 sched=0/0 cgrp=apps/bg_non_interactive handle=-1209206344
04-18 11:39:14.073: I/dalvikvm(979):   | state=R schedstat=( 4210000000 85770000000 885 ) utm=395 stm=26 core=0
04-18 11:39:14.073: I/dalvikvm(979):   at java.lang.AbstractStringBuilder.enlargeBuffer(AbstractStringBuilder.java:~94)
04-18 11:39:14.073: I/dalvikvm(979):   at java.lang.AbstractStringBuilder.append0(AbstractStringBuilder.java:124)
04-18 11:39:14.073: I/dalvikvm(979):   at java.lang.StringBuffer.append(StringBuffer.java:278)
04-18 11:39:14.073: I/dalvikvm(979):   at java.io.StringWriter.write(StringWriter.java:123)
04-18 11:39:14.073: I/dalvikvm(979):   at com.android.internal.util.FastPrintWriter.flushLocked(FastPrintWriter.java:358)
04-18 11:39:14.073: I/dalvikvm(979):   at com.android.internal.util.FastPrintWriter.flush(FastPrintWriter.java:387)
04-18 11:39:14.073: I/dalvikvm(979):   at android.util.Log.getStackTraceString(Log.java:335)
04-18 11:39:14.073: I/dalvikvm(979):   at android.util.Slog.e(Slog.java:77)
04-18 11:39:14.073: I/dalvikvm(979):   at com.android.internal.os.RuntimeInit$UncaughtHandler.uncaughtException(RuntimeInit.java:88)
04-18 11:39:14.073: I/dalvikvm(979):   at java.lang.ThreadGroup.uncaughtException(ThreadGroup.java:693)
04-18 11:39:14.083: I/dalvikvm(979):   at java.lang.ThreadGroup.uncaughtException(ThreadGroup.java:690)
04-18 11:39:14.083: I/Process(979): Sending signal. PID: 979 SIG: 9

Answer 1

内存不足不是异常，而是错误——程序不太可能恢复的状态。错误不是异常，因此捕获异常不起作用。

如果你真的想捕获它，请使用 OutOfMemoryError :

try {
  expensiveMethod();
} catch (OutOfMemoryError e) {
  // ...
}

请注意，如果您发现这一点，那么您所说的是“我知道如何处理内存不足的情况”。这极不可能是真的；您的程序已经处于不稳定状态，任何进一步的分配都可能会触发另一个 OOME。

Is there a way to get more memory [...]?

正确的解决方案是让您的程序一次使用更少的资源。例如，您可以将求解器的工作分成离散的 block ，并在工作量太大时增量存储您的工作(例如，通过将其写入磁盘)。稍后，当您需要最终解决方案时，将已解析的 block 加载回内存并组装它们。

Is there a way [...] to stop the solver before the memory is full?

您可以监控应用当前的内存使用情况:

MemoryInfo mi = new MemoryInfo();
ActivityManager a = (ActivityManager)getSystemService(ACTIVITY_SERVICE);
a.getMemoryInfo(mi);

并据此采取一些行动。但一旦你确实内存不足，再做任何有用的事情可能就太晚了。