error日志显示不全的问题，-XX:-OmitStackTraceInFastThrow

1、jvm启动参数中没有配置-XX:-OmitStackTraceInFastThrow，参数：OmitStackTraceInFastThrow字面意思是省略异常栈信息从而快速抛出。

相关源码：

  // If this throw happens frequently, an uncommon trap might cause
  // a performance pothole.  If there is a local exception handler,
  // and if this particular bytecode appears to be deoptimizing often,
  // let us handle the throw inline, with a preconstructed instance.
  // Note:   If the deopt count has blown up, the uncommon trap
  // runtime is going to flush this nmethod, not matter what.
  // 这里要满足两个条件：1.检测到频繁抛出异常，2. OmitStackTraceInFastThrow为true，或StackTraceInThrowable为false
  if (treat_throw_as_hot
      && (!StackTraceInThrowable || OmitStackTraceInFastThrow)) {
    // If the throw is local, we use a pre-existing instance and
    // punt on the backtrace.  This would lead to a missing backtrace
    // (a repeat of 4292742) if the backtrace object is ever asked
    // for its backtrace.
    // Fixing this remaining case of 4292742 requires some flavor of
    // escape analysis.  Leave that for the future.
    ciInstance* ex_obj = NULL;
    switch (reason) {
    case Deoptimization::Reason_null_check:
      ex_obj = env()->NullPointerException_instance();
      break;
    case Deoptimization::Reason_div0_check:
      ex_obj = env()->ArithmeticException_instance();
      break;
    case Deoptimization::Reason_range_check:
      ex_obj = env()->ArrayIndexOutOfBoundsException_instance();
      break;
    case Deoptimization::Reason_class_check:
      if (java_bc() == Bytecodes::_aastore) {
        ex_obj = env()->ArrayStoreException_instance();
      } else {
        ex_obj = env()->ClassCastException_instance();
      }
      break;
    }
    ... ...
}

2、OmitStackTraceInFastThrow和StackTraceInThrowable都默认为true。

所以条件 (!StackTraceInThrowable || OmitStackTraceInFastThrow)为true，即JVM默认开启了Fast Throw优化。

如果想关闭这个优化，配置-XX:-OmitStackTraceInFastThrow，StackTraceInThrowable保持默认配置-XX:+OmitStackTraceInFastThrow即可。

JVM只对几个特定类型异常开启了Fast Throw优化，这些异常包括:

• NullPointerException
• ArithmeticException
• ArrayIndexOutOfBoundsException
• ArrayStoreException
• ClassCastException

 

3、下面写个循环调用空指针异常测试一下：在循环了2800多次后，还是能正常打出堆栈信息。再之后就简化了异常输出。

 

 

 

4、修改JVM 启动参数，添加OmitStackTraceInFastThrow后。循环7000次异常信息还是正常输出。