/**
* method to extract the next monitor entry from the instrumentation memory. assumes that
* nextEntry is the offset into the byte array at which to start the search for the next entry.
* method leaves next entry pointing to the next entry or to the end of data.
*/
protected Monitor getNextMonitorEntry() throws MonitorException {
Monitor monitor = null;
// entries are always 4 byte aligned.
if ((nextEntry % 4) != 0) {
throw new MonitorStructureException("Entry index not properly aligned: " + nextEntry);
}
// protect against a corrupted shared memory region.
if ((nextEntry < 0) || (nextEntry > buffer.limit())) {
throw new MonitorStructureException(
"Entry index out of bounds: nextEntry = " + nextEntry + ", limit = " + buffer.limit());
}
// check for the end of the buffer
if (nextEntry == buffer.limit()) {
lognl("getNextMonitorEntry():" + " nextEntry == buffer.limit(): returning");
return null;
}
buffer.position(nextEntry);
int entryStart = buffer.position();
int entryLength = buffer.getInt();
// check for valid entry length
if ((entryLength < 0) || (entryLength > buffer.limit())) {
throw new MonitorStructureException("Invalid entry length: entryLength = " + entryLength);
}
// check if last entry occurs before the eof.
if ((entryStart + entryLength) > buffer.limit()) {
throw new MonitorStructureException(
"Entry extends beyond end of buffer: "
+ " entryStart = "
+ entryStart
+ " entryLength = "
+ entryLength
+ " buffer limit = "
+ buffer.limit());
}
if (entryLength == 0) {
// end of data
return null;
}
int nameLength = buffer.getInt();
int vectorLength = buffer.getInt();
byte dataType = buffer.get();
byte flags = buffer.get();
Units u = Units.toUnits(buffer.get());
Variability v = Variability.toVariability(buffer.get());
boolean supported = (flags & 0x01) != 0;
// defend against corrupt entries
if ((nameLength <= 0) || (nameLength > entryLength)) {
throw new MonitorStructureException("Invalid Monitor name length: " + nameLength);
}
if ((vectorLength < 0) || (vectorLength > entryLength)) {
throw new MonitorStructureException("Invalid Monitor vector length: " + vectorLength);
}
// read in the perfData item name, casting bytes to chars. skip the
// null terminator
//
byte[] nameBytes = new byte[nameLength - 1];
for (int i = 0; i < nameLength - 1; i++) {
nameBytes[i] = buffer.get();
}
// convert name into a String
String name = new String(nameBytes, 0, nameLength - 1);
if (v == Variability.INVALID) {
throw new MonitorDataException(
"Invalid variability attribute:" + " entry index = " + perfDataItem + " name = " + name);
}
if (u == Units.INVALID) {
throw new MonitorDataException(
"Invalid units attribute: " + " entry index = " + perfDataItem + " name = " + name);
}
int offset;
if (vectorLength == 0) {
// scalar Types
if (dataType == BasicType.LONG.intValue()) {
offset = entryStart + entryLength - 8; /* 8 = sizeof(long) */
buffer.position(offset);
LongBuffer lb = buffer.asLongBuffer();
lb.limit(1);
monitor = new PerfLongMonitor(name, u, v, supported, lb);
perfDataItem++;
} else {
// bad data types.
throw new MonitorTypeException(
"Invalid Monitor type:"
+ " entry index = "
+ perfDataItem
+ " name = "
+ name
+ " type = "
+ dataType);
}
} else {
// vector types
if (dataType == BasicType.BYTE.intValue()) {
if (u != Units.STRING) {
// only byte arrays of type STRING are currently supported
throw new MonitorTypeException(
"Invalid Monitor type:"
+ " entry index = "
+ perfDataItem
+ " name = "
+ name
+ " type = "
+ dataType);
}
offset = entryStart + PERFDATA_NAME_OFFSET + nameLength;
buffer.position(offset);
ByteBuffer bb = buffer.slice();
bb.limit(vectorLength);
bb.position(0);
if (v == Variability.CONSTANT) {
monitor = new PerfStringConstantMonitor(name, supported, bb);
} else if (v == Variability.VARIABLE) {
monitor = new PerfStringVariableMonitor(name, supported, bb, vectorLength - 1);
} else {
// Monotonically increasing byte arrays are not supported
throw new MonitorDataException(
"Invalid variability attribute:"
+ " entry index = "
+ perfDataItem
+ " name = "
+ name
+ " variability = "
+ v);
}
perfDataItem++;
} else {
// bad data types.
throw new MonitorTypeException(
"Invalid Monitor type:"
+ " entry index = "
+ perfDataItem
+ " name = "
+ name
+ " type = "
+ dataType);
}
}
// setup index to next entry for next iteration of the loop.
nextEntry = entryStart + entryLength;
return monitor;
}
/**
* method to repair the 1.4.2 parallel scavenge counters that are incorrectly initialized by the
* JVM when UseAdaptiveSizePolicy is set. This bug couldn't be fixed for 1.4.2 FCS due to putback
* restrictions.
*/
private void kludgeMantis(Map<String, Monitor> map, StringMonitor args) {
/*
* the HotSpot 1.4.2 JVM with the +UseParallelGC option along
* with its default +UseAdaptiveSizePolicy option has a bug with
* the initialization of the sizes of the eden and survivor spaces.
* See bugid 4890736.
*
* note - use explicit 1.4.2 counter names here - don't update
* to latest counter names or attempt to find aliases.
*/
String cname = "hotspot.gc.collector.0.name";
StringMonitor collector = (StringMonitor) map.get(cname);
if (collector.stringValue().compareTo("PSScavenge") == 0) {
boolean adaptiveSizePolicy = true;
/*
* HotSpot processes the -XX:Flags/.hotspotrc arguments prior to
* processing the command line arguments. This allows the command
* line arguments to override any defaults set in .hotspotrc
*/
cname = "hotspot.vm.flags";
StringMonitor flags = (StringMonitor) map.get(cname);
String allArgs = flags.stringValue() + " " + args.stringValue();
/*
* ignore the -XX: prefix as it only applies to the arguments
* passed from the command line (i.e. the invocation api).
* arguments passed through .hotspotrc omit the -XX: prefix.
*/
int ahi = allArgs.lastIndexOf("+AggressiveHeap");
int aspi = allArgs.lastIndexOf("-UseAdaptiveSizePolicy");
if (ahi != -1) {
/*
* +AggressiveHeap was set, check if -UseAdaptiveSizePolicy
* is set after +AggressiveHeap.
*/
//
if ((aspi != -1) && (aspi > ahi)) {
adaptiveSizePolicy = false;
}
} else {
/*
* +AggressiveHeap not set, must be +UseParallelGC. The
* relative position of -UseAdaptiveSizePolicy is not
* important in this case, as it will override the
* UseParallelGC default (+UseAdaptiveSizePolicy) if it
* appears anywhere in the JVM arguments.
*/
if (aspi != -1) {
adaptiveSizePolicy = false;
}
}
if (adaptiveSizePolicy) {
// adjust the buggy AdaptiveSizePolicy size counters.
// first remove the real counters.
String eden_size = "hotspot.gc.generation.0.space.0.size";
String s0_size = "hotspot.gc.generation.0.space.1.size";
String s1_size = "hotspot.gc.generation.0.space.2.size";
map.remove(eden_size);
map.remove(s0_size);
map.remove(s1_size);
// get the maximum new generation size
String new_max_name = "hotspot.gc.generation.0.capacity.max";
LongMonitor new_max = (LongMonitor) map.get(new_max_name);
/*
* replace the real counters with pseudo counters that are
* initialized to to the correct values. The maximum size of
* the eden and survivor spaces are supposed to be:
* max_eden_size = new_size - (2*alignment).
* max_survivor_size = new_size - (2*alignment).
* since we don't know the alignment value used, and because
* of other parallel scavenge bugs that result in oversized
* spaces, we just set the maximum size of each space to the
* full new gen size.
*/
Monitor monitor = null;
LongBuffer lb = LongBuffer.allocate(1);
lb.put(new_max.longValue());
monitor = new PerfLongMonitor(eden_size, Units.BYTES, Variability.CONSTANT, false, lb);
map.put(eden_size, monitor);
monitor = new PerfLongMonitor(s0_size, Units.BYTES, Variability.CONSTANT, false, lb);
map.put(s0_size, monitor);
monitor = new PerfLongMonitor(s1_size, Units.BYTES, Variability.CONSTANT, false, lb);
map.put(s1_size, monitor);
}
}
}