我正在尝试使用VisualVM来配置我的程序，但它总是崩溃，通常会出现相同的错误消息：
Waiting...
Profiler Agent: Waiting for connection on port 5140 (Protocol version: 15)
Profiler Agent: Established connection with the tool
Profiler Agent: Local accelerated session
Starting test 0
#
# A fatal error has been detected by the Java Runtime Environment:
#
# EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x00000000c12e9d20, pid=4808, tid=11472
#
# JRE version: Java(TM) SE Runtime Environment (8.0_31-b13) (build 1.8.0_31-b13)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (25.31-b07 mixed mode windows-amd64 compressed oops)
# Problematic frame:
# C 0x00000000c12e9d20
#
# Failed to write core dump. Minidumps are not enabled by default on client versions of Windows
#
# An error report file with more information is saved as:
# C:\Users\Brendon\workspace\JavaFx\hs_err_pid4808.log
Compiled method (c1) 10245 952 3 pathfinderGameTest.Pathfinder$$Lambda$4/1163157884::get$Lambda (10 bytes)
total in heap [0x00000000027d72d0,0x00000000027d7798] = 1224
relocation [0x00000000027d73f0,0x00000000027d7430] = 64
main code [0x00000000027d7440,0x00000000027d7620] = 480
stub code [0x00000000027d7620,0x00000000027d76b0] = 144
oops [0x00000000027d76b0,0x00000000027d76b8] = 8
metadata [0x00000000027d76b8,0x00000000027d76d0] = 24
scopes data [0x00000000027d76d0,0x00000000027d7730] = 96
scopes pcs [0x00000000027d7730,0x00000000027d7790] = 96
dependencies [0x00000000027d7790,0x00000000027d7798] = 8
#
# If you would like to submit a bug report, please visit:
# http://bugreport.java.com/bugreport/crash.jsp
#
Profiler Agent: JNI OnLoad Initializing...
Profiler Agent: JNI OnLoad Initialized successfully
Profiler Agent Warning: JVMTI classLoadHook: class name is null.
Profiler Agent Warning: JVMTI classLoadHook: class name is null.
Profiler Agent Warning: JVMTI classLoadHook: class name is null.
Profiler Agent Warning: JVMTI classLoadHook: class name is null.
Profiler Agent Warning: JVMTI classLoadHook: class name is null.
Profiler Agent Warning: JVMTI classLoadHook: class name is null.
Profiler Agent Warning: JVMTI classLoadHook: class name is null.
Profiler Agent Warning: JVMTI classLoadHook: class name is null.
Profiler Agent Warning: JVMTI classLoadHook: class name is null.
Profiler Agent Warning: JVMTI classLoadHook: class name is null.
Profiler Agent Warning: JVMTI classLoadHook: class name is null.
VisualVM设法给我一个非常快速的快照（约60ms），但我不确定这样的快速测试是多么可靠。
我遵循了https://msdn.microsoft.com/en-us/library/system.net.sockets.udpclient(v=vs.110).aspx条款，但没有改变任何内容。无论如何我都在使用Java7，所以它甚至不应该是一个问题。
这是我试图描述的代码：
package pathfinderGameTest;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Date;
import java.util.Deque;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Scanner;
import java.util.function.BiConsumer;
import utils.Duple;
public class Pathfinder<T> {
//To track walls
Area<T> area;
public Pathfinder(Area<T> a) {
area = a;
}
/**
* Preset offsets representing each of the four directions.
*/
private static final List<Duple<Double>> fourDirectionOffsets = Collections.unmodifiableList(Arrays.asList(
new Duple<Double>(1.0,0.0), new Duple<Double>(-1.0,0.0), new Duple<Double>(0.0,1.0), new Duple<Double>(0.0,-1.0) ));
/**
* Finds a path from aStart to bGoal, taking into consideration walls
*
* @param aStart The start position
* @param bGoal The goal position
* @return A list representing the path from the start to the goal
*/
public List<Duple<Double>> findPathFromAToB(Duple<Double> aStart, Duple<Double> bGoal) {
Deque<Duple<Double>> frontier = new ArrayDeque<>();
Map<Duple<Double>, Duple<Double>> cameFrom = new HashMap<>();
frontier.push(aStart);
while (!frontier.isEmpty()) {
Duple<Double> current = frontier.pop();
if (current.equals(bGoal)) break;
List<Duple<Double>> neighbors = cellsAround(current, fourDirectionOffsets);
neighbors.stream()
.filter(location -> !cameFrom.containsKey(location) && area.cellIsInBounds(location) && area.getCellAt(location) == null)
.forEach( neighbor -> {
frontier.add(neighbor);
cameFrom.put(neighbor, current);
});
}
return reconstructPath(cameFrom, aStart, bGoal);
}
/**
* Transforms a backtracking map into a path
*
* @param cameFrom Backtracking map
* @param start Start position
* @param goal Goal position
* @return A list representing the path from the start to the goal
*/
private static List<Duple<Double>> reconstructPath(Map<Duple<Double>, Duple<Double>> cameFrom, Duple<Double> start, Duple<Double> goal) {
List<Duple<Double>> path = new ArrayList<>();
//path.add(goal);
Duple<Double> current = goal;
do {
if (current != goal) {
path.add(current);
}
current = cameFrom.get(current);
} while (current != null && !current.equals(start));
Collections.reverse(path);
return path;
}
/**
* Calculates the cells surrounding pos as indicated by the given offsets
* @param pos The position to find the surrounding cells of
* @param offsets Positions relative to pos to check
* @return
*/
private static List<Duple<Double>> cellsAround(Duple<Double> pos, List<Duple<Double>> offsets) {
List<Duple<Double>> surroundingCells = new ArrayList<>();
/*offsets.stream()
.map( offset -> pos.map(offset, (x1, x2) -> x1 + x2) )
.forEach(surroundingCells::add);*/
for (Duple<Double> offset : offsets) {
surroundingCells.add( pos.map(offset, (x1, x2) -> x1 + x2) );
}
return surroundingCells;
}
public static void main(String[] args) {
Scanner s = new Scanner(System.in);
System.out.println("Waiting...");
s.nextLine();
List<Long> times = new ArrayList<>();
for (int tests = 0; tests < 900; tests++) {
System.out.println("Starting test " + tests);
long startT = new Date().getTime();
Area<Wall> a = new Area<>(500, 500);
Duple<Double> source = new Duple<>(0.0, 0.0);
Duple<Double> target = new Duple<>(500.0, 500.0);
Pathfinder<Wall> p = new Pathfinder<>(a);
List<Duple<Double>> path = p.findPathFromAToB(source, target);
times.add( (new Date().getTime()) - startT );
}
System.out.println("\n\n");
long sum = 0;
for (long t : times) {
System.out.println(t);
sum += t;
}
System.out.println("Average: " + ((double)sum / times.size() / 1000) + " seconds.");
}
}