Throwable instance.
* *
The test tries to occupy all of memory available in the heap by
* allocating lots of new Object() instances. Instances of the
* type Object are the smallest objects, so they apparently should
* occupy most fine-grained fragments in the heap and leave no free space for
* new Throwable instance. After that, the test provokes various
* exceptions (e.g.: by executing integer division by 0 and so on), and checks
* if appropriate exceptions are thrown.
*
*
Note, that memory occupation is terminated if memory allocation slows
* down crucially. This is a workaround intended to avoid the HotSpot bug:
*
* #4248801 (P1/S5) slow memory allocation when heap is almost exhausted
*
*
There is also a workaround involved to avoid the following bugs known
* for HotSpot and for classic VM:
*
* #4239841 (P1/S5) 1.1: poor garbage collector performance
*
* #4245060 (P4/S5) poor garbage collector performance
*
However, printing of the test's error messages, warnings, and of
* execution trace may fail even so. If the test fails due to poor GC
* performance, exit status 96 is returned instead of 97.
*
*
Also note, that the test needs a lot of memory to start up, so it should
* not run under older JDK 1.1.x release due to its poor heap utilization.
*/
public class except002 {
/**
* Either allow or supress printing of execution trace.
*/
private static boolean TRACE_ON = false;
/**
* Either allow or supress printing of warning messages.
*/
private static final boolean WARN_ON = true;
/*
* Storage for a lot of tiny objects
* "static volatile" keywords are for preventing heap optimization
*/
public static volatile Object pool[] = null;
/**
* Temporary log for error messages, warnings and/or execution trace.
*
* @see #messages
*/
private static String log[] = new String[1000]; // up to 1000 messages
/**
* How many messages were submitted to the log.
*
* @see #log
*/
private static int messages = 0;
/**
* Re-call to the method run(out) (ignore args[]),
* and print the test summary - either test passed of failed.
*/
public static int run(String args[], PrintStream out) {
if (args.length > 0) {
if (args[0].toLowerCase().startsWith("-v"))
TRACE_ON = true;
}
int exitCode = run(out);
pool = null;
System.gc();
// Print the log[] and the test summary:
try {
for (int i = 0; i < messages; i++)
out.println(log[i]);
if (exitCode == 0) {
if (TRACE_ON)
out.println("Test passed.");
} else
out.println("Test failed.");
} catch (OutOfMemoryError oome) {
// Poor performance of garbage collector:
exitCode = 1;
}
return exitCode;
}
/**
* Allocate as much Object instances as possible to bring JVM
* into stress, and then check if exceptions are correctly thrown accordingly
* to various situations like integer division by 0, etc.
*/
private static int run(PrintStream out) {
out.println("# While printing this message, JVM seems to initiate the output");
out.println("# stream, so that it will not need more memory to print later,");
out.println("# when the heap would fail to provide more memory.");
out.println("# ");
out.println("# Note, that the test maintains especial static log[] field in");
out.println("# order to avoid printing when the heap seems exhausted.");
out.println("# Nevertheless, printing could arise OutOfMemoryError even");
out.println("# after all the memory allocated by the test is released.");
out.println("# ");
out.println("# That problem is caused by the known JDK/HotSpot bugs:");
out.println("# 4239841 (P1/S5) 1.1: poor garbage collector performance");
out.println("# 4245060 (P4/S5) poor garbage collector performance");
out.println("# ");
out.println("# This message is just intended to work-around that problem.");
out.println("# If printing should fail even so, the test will return the");
out.println("# exit status 96 instead of 97 to indicate the problem.");
// Prepare some items, which will be used by the test:
Object trash = null;
// Sum up exit code:
int exitCode = 0; // apparently PASSED
int skipped = 0; // some checks may correctly suffer OutOfMemoryError
// Allocate repository for a lots of tiny objects:
for (int size = 1 << 30; size > 0 && pool == null; size >>= 1)
try {
pool = new Object[size];
} catch (OutOfMemoryError oome) {
}
if (pool == null)
throw new Error("HS bug: cannot allocate new Object[1]");
int poolSize = pool.length;
int index = 0;
// Sum up time spent, when it was hard to JVM to allocate next object
// (i.e.: when JVM has spent more than 1 second to allocate new object):
double totalDelay = 0;
long timeMark = System.currentTimeMillis();
try {
for (; index < poolSize; index++) {
//-------------------------
pool[index] = new Object();
long nextTimeMark = System.currentTimeMillis();
long elapsed = nextTimeMark - timeMark;
timeMark = nextTimeMark;
//----------------------
if (elapsed > 1000) {
double seconds = elapsed / 1000.0;
if (TRACE_ON)
out.println(
"pool[" + index + "]=new Object(); // elapsed " + seconds + "s");
totalDelay += seconds;
if (totalDelay > 60) {
if (TRACE_ON)
out.println(
"Memory allocation became slow; so, heap seems exhausted.");
break;
}
}
}
} catch (OutOfMemoryError oome) {
if (TRACE_ON)
log[messages++] = "Heap seems exhausted - OutOfMemoryError thrown.";
// Do not release any byte once allocated:
pool[index++] = oome;
}
if (index > poolSize - 1000) {
if (WARN_ON)
log[messages++] = "Warning: pool[] is full; so, checks would not be enough hard...";
}
// Check ClassNotFoundException (positive):
try {
trash = Class.forName("nsk.stress.except.except002$Abra$Cadabra"); // correct - should pass
// trash = Class.forName("nsk.stress.except.except002.Abra.Cadabra"); // incorrect - should fail
if (TRACE_ON)
log[messages++] = "Success: ClassNotFoundException (positive)";
} catch (ClassNotFoundException cnfe) {
log[messages++] = "Failure: ClassNotFoundException (positive)";
exitCode = 2;
} catch (OutOfMemoryError oome) {
if (WARN_ON)
log[messages++] = "Skipped: ClassNotFoundException (positive)";
skipped++;
}
return exitCode;
}
/**
* Re-call to run(args,out), and return JCK-like exit status.
* (The stream out is assigned to System.out here.)
*
* @see #run(String[], PrintStream)
*/
public static void main(String args[]) {
Thread.setDefaultUncaughtExceptionHandler(new Thread.UncaughtExceptionHandler() {
// Last try. If there is some exception outside the code, test should end correctly
@Override
public void uncaughtException(Thread t, Throwable e) {
try {
pool = null;
log = null;
System.gc();
if (e instanceof OutOfMemoryError) {
try {
System.out.println("OOME : Test Skipped");
System.exit(0);
} catch (Throwable ignore) {
} // No code in the handler can provoke correct exceptions.
} else {
e.printStackTrace();
throw (RuntimeException) e;
}
} catch (OutOfMemoryError oome) {
}
}
});
int exitCode = run(args, System.out);
System.exit(exitCode + 95);
// JCK-like exit status.
}
/**
* This class should be used to check ClassNotFoundException
* and IllegalAccessException.
*/
private static class Abra {
/**
* Will try to incorrectly find this class as Cadabra
* instead of Abra$Cadabra.
*/
public static class Cadabra {
}
}
}