public static String getMemoryInformation() {
Runtime rt = Runtime.getRuntime();
DecimalFormat df = new DecimalFormat("###,###,###,###");
return "used = "
+ df.format(rt.totalMemory() - rt.freeMemory())
+ " free = "
+ rt.freeMemory()
+ " total = "
+ rt.totalMemory()
+ " max = "
+ rt.maxMemory();
}
public static void main(String[] args) throws Exception{
//free和use和total均为KB
long free=0;
long use=0;
long total=0;
int kb=1024;
Runtime rt=Runtime.getRuntime();
total=rt.totalMemory();
free=rt.freeMemory();
use=total-free;
System.out.println("系统内存已用的空间为："+use/kb+" MB");
System.out.println("系统内存的空闲空间为："+free/kb+" MB");
System.out.println("系统总内存空间为："+total/kb+" MB");
OperatingSystemMXBean osmxb = (OperatingSystemMXBean) ManagementFactory.getOperatingSystemMXBean();
long physicalFree=osmxb.getFreePhysicalMemorySize()/kb;
long physicalTotal=osmxb.getTotalPhysicalMemorySize()/kb;
long physicalUse=physicalTotal-physicalFree;
String os=System.getProperty("os.name");
System.out.println("操作系统的版本："+os);
System.out.println("系统物理内存已用的空间为："+physicalFree+" MB");
System.out.println("系统物理内存的空闲空间为："+physicalUse+" MB");
System.out.println("总物理内存："+physicalTotal+" MB");
// 获得线程总数
ThreadGroup parentThread;
for (parentThread = Thread.currentThread().getThreadGroup(); parentThread.getParent() != null; parentThread = parentThread.getParent())
;
int totalThread = parentThread.activeCount();
System.out.println("获得线程总数:"+totalThread);
}
private void handleException(Realm realm, OutOfMemoryError e) {
// Try to recover after OOM.
Runtime rt = Runtime.getRuntime();
long beforeGc = rt.freeMemory();
rt.gc();
long afterGc = rt.freeMemory();
if (afterGc > beforeGc && (afterGc - beforeGc) < 50_000_000) {
// Calling gc() cleared less than 50MB, assume unrecoverable OOM and rethrow error.
throw e;
}
// Create script exception with stacktrace from oom-error.
ScriptException exception =
newInternalError(realm.defaultContext(), Messages.Key.OutOfMemoryVM);
exception.setStackTrace(e.getStackTrace());
handleException(realm, exception);
}
public static void fullGC(boolean verbose) {
if (verbose)
System.out.print(
new Date().toString()
+ ' '
+ String.valueOf((RUNTIME.totalMemory() - RUNTIME.freeMemory()) / 1024L)
+ "Kb used");
long isFree = RUNTIME.freeMemory();
long wasFree;
do {
wasFree = isFree;
RUNTIME.runFinalization();
RUNTIME.gc();
isFree = RUNTIME.freeMemory();
} while (isFree > wasFree);
if (verbose)
System.out.println(
" --> "
+ String.valueOf((RUNTIME.totalMemory() - RUNTIME.freeMemory()) / 1024L)
+ "Kb used");
}
@Override
public DiskData build() throws IOException {
meta.assign(parser);
meta.dirty = true;
// calculate optimized output buffer sizes to reduce disk fragmentation
final Runtime rt = Runtime.getRuntime();
final long max = Math.min(1 << 22, rt.maxMemory() - rt.freeMemory() >> 2);
int bs = (int) Math.min(meta.filesize, max);
bs = Math.max(IO.BLOCKSIZE, bs - bs % IO.BLOCKSIZE);
// drop old database (if available) and create new one
DropDB.drop(dbname, sopts);
sopts.dbpath(dbname).md();
elemNames = new Names(meta);
attrNames = new Names(meta);
try {
tout = new DataOutput(new TableOutput(meta, DATATBL));
xout = new DataOutput(meta.dbfile(DATATXT), bs);
vout = new DataOutput(meta.dbfile(DATAATV), bs);
sout = new DataOutput(meta.dbfile(DATATMP), bs);
final Performance perf = Prop.debug ? new Performance() : null;
Util.debug(tit() + DOTS);
parse();
if (Prop.debug) Util.errln(" " + perf + " (" + Performance.getMemory() + ')');
} catch (final IOException ex) {
try {
close();
} catch (final IOException ignored) {
}
throw ex;
}
close();
// copy temporary values into database table
try (final DataInput in = new DataInput(meta.dbfile(DATATMP))) {
final TableAccess ta = new TableDiskAccess(meta, true);
for (; spos < ssize; ++spos) ta.write4(in.readNum(), 8, in.readNum());
ta.close();
}
meta.dbfile(DATATMP).delete();
// return database instance
return new DiskData(meta, elemNames, attrNames, path, ns);
}
private void doClean(timerEvent ev) {
// Cleaner event
if (VERBOSE) System.err.println("-- Cleaning up packetTable");
// Might cause some recent packets to be dropped
packetTable.clear();
if (VERBOSE) {
Runtime r = Runtime.getRuntime();
System.err.println(
"TOTAL: " + r.totalMemory() / 1024 + "KB FREE: " + r.freeMemory() / 1024 + "KB");
}
// Reregister timer event
timer.registerEvent(CLEAN_TIMER_FREQUENCY, ev, mySink);
}
public String toString() {
String result = "f=" + (runtime.freeMemory() / MEGA) + "/";
result += "t=" + (runtime.totalMemory() / MEGA) + "/";
result += "m=" + (runtime.maxMemory() / MEGA) + "Mb";
return result;
}
public static long getUsedMemory() {
Runtime rt = Runtime.getRuntime();
return rt.totalMemory() - rt.freeMemory();
}