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6977034: Thread.getState() very slow

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Directly map the threadStatus value to Thread.State

Reviewed-by: emcmanus, dholmes
This commit is contained in:
Mandy Chung 2010-12-08 10:45:28 -08:00
parent d91f2b34af
commit e54cb28a96
2 changed files with 30 additions and 61 deletions
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2
jdk/src/share/classes/java/lang/Thread.java
View File

@ -209,7 +209,7 @@ class Thread implements Runnable {
* initialized to indicate thread 'not yet started'
*/
private int threadStatus = 0;
private volatile int threadStatus = 0;
private static synchronized long nextThreadID() {

89
jdk/src/share/classes/sun/misc/VM.java
View File

@ -25,6 +25,7 @@
package sun.misc;
import static java.lang.Thread.State.*;
import java.util.Properties;
import java.util.HashMap;
import java.util.Map;
@ -332,69 +333,37 @@ public class VM {
}
}
/**
* Returns Thread.State for the given threadStatus
*/
public static Thread.State toThreadState(int threadStatus) {
// Initialize the threadStateMap
initThreadStateMap();
Thread.State s = threadStateMap.get(threadStatus);
if (s == null) {
// default to RUNNABLE if the threadStatus value is unknown
s = Thread.State.RUNNABLE;
}
return s;
}
// a map of threadStatus values to the corresponding Thread.State
private static Map<Integer, Thread.State> threadStateMap = null;
private static Map<Integer, String> threadStateNames = null;
private synchronized static void initThreadStateMap() {
if (threadStateMap != null) {
return;
}
final Thread.State[] ts = Thread.State.values();
final int[][] vmThreadStateValues = new int[ts.length][];
final String[][] vmThreadStateNames = new String[ts.length][];
getThreadStateValues(vmThreadStateValues, vmThreadStateNames);
threadStateMap = new HashMap<Integer, Thread.State>();
threadStateNames = new HashMap<Integer, String>();
for (int i = 0; i < ts.length; i++) {
String state = ts[i].name();
int[] values = null;
String[] names = null;
for (int j = 0; j < ts.length; j++) {
if (vmThreadStateNames[j][0].startsWith(state)) {
values = vmThreadStateValues[j];
names = vmThreadStateNames[j];
}
}
if (values == null) {
throw new InternalError("No VM thread state mapped to " +
state);
}
if (values.length != names.length) {
throw new InternalError("VM thread state values and names " +
" mapped to " + state + ": length not matched" );
}
for (int k = 0; k < values.length; k++) {
threadStateMap.put(values[k], ts[i]);
threadStateNames.put(values[k], names[k]);
}
if ((threadStatus & JVMTI_THREAD_STATE_RUNNABLE) != 0) {
return RUNNABLE;
} else if ((threadStatus & JVMTI_THREAD_STATE_BLOCKED_ON_MONITOR_ENTER) != 0) {
return BLOCKED;
} else if ((threadStatus & JVMTI_THREAD_STATE_WAITING_INDEFINITELY) != 0) {
return WAITING;
} else if ((threadStatus & JVMTI_THREAD_STATE_WAITING_WITH_TIMEOUT) != 0) {
return TIMED_WAITING;
} else if ((threadStatus & JVMTI_THREAD_STATE_TERMINATED) != 0) {
return TERMINATED;
} else if ((threadStatus & JVMTI_THREAD_STATE_ALIVE) == 0) {
return NEW;
} else {
return RUNNABLE;
}
}
// Fill in vmThreadStateValues with int arrays, each of which contains
// the threadStatus values mapping to the Thread.State enum constant.
// Fill in vmThreadStateNames with String arrays, each of which contains
// the name of each threadStatus value of the format:
// <Thread.State.name()>[.<Substate name>]
// e.g. WAITING.OBJECT_WAIT
//
private native static void getThreadStateValues(int[][] vmThreadStateValues,
String[][] vmThreadStateNames);
/* The threadStatus field is set by the VM at state transition
* in the hotspot implementation. Its value is set according to
* the JVM TI specification GetThreadState function.
*/
private final static int JVMTI_THREAD_STATE_ALIVE = 0x0001;
private final static int JVMTI_THREAD_STATE_TERMINATED = 0x0002;
private final static int JVMTI_THREAD_STATE_RUNNABLE = 0x0004;
private final static int JVMTI_THREAD_STATE_BLOCKED_ON_MONITOR_ENTER = 0x0400;
private final static int JVMTI_THREAD_STATE_WAITING_INDEFINITELY = 0x0010;
private final static int JVMTI_THREAD_STATE_WAITING_WITH_TIMEOUT = 0x0020;
static {
initialize();