@ -28,6 +28,9 @@ package de.anomic.server;
import de.anomic.server.logging.serverLog ;
import de.anomic.tools.yFormatter ;
/ * *
* Use this to get information about memory usage or try to free some memory
* /
public class serverMemory {
private static final Runtime runtime = Runtime . getRuntime ( ) ;
@ -38,6 +41,11 @@ public class serverMemory {
private static long lastGC ;
/ * *
* Runs the garbage collector if last garbage collection is more than last millis ago
* @param last time which must be passed since lased gc
* @param info additional info for log
* /
public final synchronized static void gc ( int last , String info ) { // thq
long elapsed = System . currentTimeMillis ( ) - lastGC ;
if ( elapsed > last ) {
@ -50,11 +58,15 @@ public class serverMemory {
}
}
/** @return the amount of freed bytes by a forced GC this method performes */
/ * *
* Tries to free count bytes
* @param count bytes
* @return the amount of freed bytes by a forced GC this method performes
* /
private static long runGC ( final boolean count ) {
final long memnow = runtime . maxMemory ( ) - runtime . totalMemory ( ) + runtime . freeMemory ( ) ;
final long mem Before = available ( ) ;
gc ( 1000 , "serverMemory.runGC(...)" ) ;
final long freed = runtime . maxMemory ( ) - runtime . totalMemory ( ) + runtime . freeMemory ( ) - memnow ;
final long freed = available( ) - memBefore ;
if ( count ) {
gcs [ gcs_pos ] = freed ;
gcs_pos = ( gcs_pos + 1 ) % gcs . length ;
@ -78,29 +90,41 @@ public class serverMemory {
return ( y = = 0 ) ? 0 : x / y ;
}
public static long free ( ) {
// memory that is free without increasing of total memory taken from os
/ * *
* memory that is free without increasing of total memory taken from os
* @return bytes
* /
public static final long free ( ) {
return runtime . freeMemory ( ) ;
}
/ * *
* Tries to free a specified amount of bytes . If the currently available memory is enough , the
* method returns < code > true < / code > without performing additional steps . Otherwise - if
* < code > gciffail < / code > is set - a Full GC is run , if < code > gciffail < / code > is set to
* < code > false < / code > and not enough memory is available , this method returns < code > false < / code > .
*
* @see serverMemory # request ( long , boolean ) for another implementation
* @param memory amount of bytes to be assured to be free
* @param gciffail if not enough memory is available , this parameter specifies whether to perform
* a Full GC to free enough RAM
* @return whether enough RAM is available
* memory that is available including increasing total memory up to maximum
* @return bytes
* /
public static final long available ( ) {
// memory that is available including increasing total memory up to maximum
return runtime . maxMemory ( ) - runtime . totalMemory ( ) + runtime . freeMemory ( ) ;
return max ( ) - total ( ) + free ( ) ;
}
/ * *
* maximum memory which the vm can use
* @return bytes
* /
public static final long max ( )
{
return runtime . maxMemory ( ) ;
}
/ * *
* currently allocated memory in the Java virtual machine ; may vary over time
* @return bytes
* /
public static final long total ( )
{
return runtime . totalMemory ( ) ;
}
/ * *
* < p > Tries to free a specified amount of bytes . < / p >
* < p >
* If the currently available memory is enough , the method returns < code > true < / code > without
@ -120,7 +144,7 @@ public class serverMemory {
* @return whether enough memory could be freed ( or is free ) or not
* /
public static boolean request ( final long size , final boolean force ) {
long avail = runtime. maxMemory ( ) - runtime . totalMemory ( ) + runtime . freeMemory ( ) ;
long avail = available ( ) ;
if ( avail > = size ) return true ;
if ( log . isFine ( ) ) {
String t = new Throwable ( "Stack trace" ) . getStackTrace ( ) [ 1 ] . toString ( ) ;
@ -130,7 +154,7 @@ public class serverMemory {
if ( force | | avg = = 0 | | avg + avail > = size ) {
// this is only called if we expect that an allocation of <size> bytes would cause the jvm to call the GC anyway
final long freed = runGC ( ! force ) ;
avail = runtime. maxMemory ( ) - runtime . totalMemory ( ) + runtime . freeMemory ( ) ;
avail = available ( ) ;
log . logInfo ( "performed " + ( ( force ) ? "explicit" : "necessary" ) + " GC, freed " + ( freed > > 10 )
+ " KB (requested/available/average: "
+ ( size > > 10 ) + " / " + ( avail > > 10 ) + " / " + ( avg > > 10 ) + " KB)" ) ;
@ -142,11 +166,19 @@ public class serverMemory {
}
}
/ * *
* memory that is currently bound in objects
* @return used bytes
* /
public static long used ( ) {
// memory that is currently bound in objects
return runtime . totalMemory ( ) - runtime . freeMemory ( ) ;
return total ( ) - free ( ) ;
}
/ * *
* Formats a number if it are bytes to greatest unit ( 1024 based )
* @param byteCount
* @return formatted String with unit
* /
public static String bytesToString ( long byteCount ) {
try {
final StringBuffer byteString = new StringBuffer ( ) ;
@ -171,21 +203,24 @@ public class serverMemory {
}
}
/ * *
* main
* @param args
* /
public static void main ( String [ ] args ) {
// try this with a jvm 1.4.2 and with a jvm 1.5 and compare results
int mb = 1024 * 1024 ;
System . out . println ( "vm: " + System . getProperty ( "java.vm.version" ) ) ;
System . out . println ( "computed max = " + ( Runtime. getRuntime ( ) . maxMemory ( ) / mb ) + " mb" ) ;
System . out . println ( "computed max = " + ( ( ) / mb ) + " mb" ) ;
int alloc = 10000 ;
Runtime rt = Runtime . getRuntime ( ) ;
byte [ ] [ ] x = new byte [ 100000 ] [ ] ;
for ( int i = 0 ; i < 100000 ; i + + ) {
x [ i ] = new byte [ alloc ] ;
if ( i % 100 = = 0 ) System . out . println ( "used = " + ( i * alloc / mb ) +
", total = " + ( rt. totalMemory ( ) / mb ) +
", free = " + ( rt. freeMemory ( ) / mb ) +
", max = " + ( rt. maxMemory ( ) / mb ) +
", avail = " + ( ( rt . maxMemory ( ) - rt . totalMemory ( ) + rt . freeMemory ( ) ) / mb ) ) ;
", total = " + ( ( ) / mb ) +
", free = " + ( ( ) / mb ) +
", max = " + ( ( ) / mb ) +
", avail = " + ( available ( ) / mb ) ) ;
}
}
danielr
17 years ago