rik/jlibcom
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

SF1603631:

Browse Source 
concurrent modification of ROT (adding or removing thread tables) causes VM crash.  The simple fix is to sychronize all accessors to the ROT.  Performance impact has not been analyzed
This commit is contained in:
clay_shooter
2006-12-08 12:42:37 +00:00
parent 5ac71b76b4
commit 3b524074a6
1 changed files with 184 additions and 180 deletions
Download Patch File Download Diff File Expand all files Collapse all files

352
src/com/jacob/com/ROT.java
View File

@@ -41,188 +41,192 @@ import java.util.WeakHashMap;
* Is [ 1116101 ] jacob-msg 0284 relevant??? * Is [ 1116101 ] jacob-msg 0284 relevant???
*/ */
public abstract class ROT { public abstract class ROT {
/** /**
* Manual garbage collection was the only option pre 1.9 * Manual garbage collection was the only option pre 1.9
*/ */
protected static final boolean USE_AUTOMATIC_GARBAGE_COLLECTION = protected static final boolean USE_AUTOMATIC_GARBAGE_COLLECTION =
"true".equalsIgnoreCase(System.getProperty("com.jacob.autogc")); "true".equalsIgnoreCase( System.getProperty( "com.jacob.autogc" ) );
/** /**
* A hash table where each element is another * A hash table where each element is another
* HashMap that represents a thread. * HashMap that represents a thread.
* Each thread HashMap contains the com objects created * Each thread HashMap contains the com objects created
* in that thread * in that thread
*/ */
private static HashMap rot = new HashMap(); private static HashMap rot = new HashMap();
/** /**
* adds a new thread storage area to rot * adds a new thread storage area to rot
* @return Map corresponding to the thread that this call was made in * @return Map corresponding to the thread that this call was made in
*/ */
protected static Map addThread() { protected synchronized static Map addThread() {
String t_name = Thread.currentThread().getName(); // should use the id here instead of the name because the name can be changed
if (rot.containsKey(t_name)){ String t_name = Thread.currentThread().getName();
// nothing to do if ( rot.containsKey( t_name ) ) {
} else { // nothing to do
Map tab = null; } else {
if (JacobObject.isDebugEnabled()){ Map tab = null;
JacobObject.debug("ROT: Automatic GC flag == "+ USE_AUTOMATIC_GARBAGE_COLLECTION if ( JacobObject.isDebugEnabled() ) {
);} JacobObject.debug( "ROT: Automatic GC flag == " + USE_AUTOMATIC_GARBAGE_COLLECTION );
if (!USE_AUTOMATIC_GARBAGE_COLLECTION){ }
tab = new HashMap(); if ( !USE_AUTOMATIC_GARBAGE_COLLECTION ) {
} else { tab = new HashMap();
tab = new WeakHashMap(); } else {
} tab = new WeakHashMap();
rot.put(t_name,tab); }
} rot.put( t_name, tab );
return getThreadObjects(false); }
} return getThreadObjects( false );
}
/**
* returns the pool for this thread if it exists. can create a new
* one if you wish by passing in TRUE
* @param createIfDoesNotExist
* @return Map the collection that holds the objects created in the current thread
*/
protected synchronized static Map getThreadObjects( boolean createIfDoesNotExist ) {
String t_name = Thread.currentThread().getName();
if ( !rot.containsKey( t_name ) && createIfDoesNotExist ) {
addThread();
}
return (Map) rot.get( t_name );
}
/** /**
* returns the pool for this thread if it exists. can create a new * Iterates across all of the entries in the Hashmap in the rot
* one if you wish by passing in TRUE * that corresponds to this thread.
* @param createIfDoesNotExist * This calls safeRelease() on each entry and then
* @return Map the collection that holds the objects created in the current thread * clears the map when done and removes it from the rot.
*/ * All traces of this thread's objects will disapear.
protected static Map getThreadObjects(boolean createIfDoesNotExist) { * This is called by COMThread in the tear down and provides a
String t_name = Thread.currentThread().getName(); * synchronous way of releasing memory
if (!rot.containsKey(t_name) && createIfDoesNotExist){ */
addThread(); protected synchronized static void clearObjects() {
} Map tab = getThreadObjects( false );
return (Map)rot.get(t_name); if ( JacobObject.isDebugEnabled() ) {
} JacobObject.debug( "ROT: " + rot.keySet().size() + " thread tables exist" );
}
if ( tab != null ) {
if ( JacobObject.isDebugEnabled() ) {
JacobObject.debug( "ROT: " + tab.keySet().size() + " objects to clear in this thread " );
}
// walk the values
Iterator it;
if ( USE_AUTOMATIC_GARBAGE_COLLECTION ) {
it = tab.keySet().iterator();
} else {
it = tab.values().iterator();
}
while ( it.hasNext() ) {
JacobObject o = (JacobObject) it.next();
if ( o != null
// can't use this cause creates a Variant if calling SafeAray
// and we get an exceptin modifying the collection while iterating
// && o.toString() != null
) {
if ( JacobObject.isDebugEnabled() ) {
if ( o instanceof SafeArray ) {
// SafeArray create more objects when calling toString()
// which causes a concurrent modification exception in HashMap
JacobObject.debug( "ROT: removing " + o.getClass().getName() );
} else {
// Variant toString() is probably always bad in here
JacobObject.debug( "ROT: removing " + o.hashCode() + "->" + o.getClass().getName() );
}
}
o.safeRelease();
}
// used to be an iterator.remove() but why bother when we're nuking them all anyway?
}
// empty the collection
tab.clear();
// remove the collection from rot
rot.remove( Thread.currentThread().getName() );
if ( JacobObject.isDebugEnabled() ) {
JacobObject.debug( "ROT: thread table cleared and removed" );
}
} else {
if ( JacobObject.isDebugEnabled() ) {
JacobObject.debug( "ROT: nothing to clear!" );
}
}
}
/** /**
* Iterates across all of the entries in the Hashmap in the rot * generates the key used to insert object into the thread's list of objects.
* that corresponds to this thread. * @param targetMap the map we need the key for. Used to make sure we create a compatabile key
* This calls safeRelease() on each entry and then * @param o JacobObject we need key for
* clears the map when done and removes it from the rot. * @return some key compatabile with hashmaps
* All traces of this thread's objects will disapear. */
* This is called by COMThread in the tear down and provides a protected static Object getMapKey( Map targetMap, JacobObject o ) {
* synchronous way of releasing memory if ( targetMap instanceof WeakHashMap ) {
*/ return o;
protected static void clearObjects() { } else {
Map tab = getThreadObjects(false); return new Integer( o.hashCode() );
if (JacobObject.isDebugEnabled()){ }
JacobObject.debug("ROT: "+rot.keySet().size()+" thread tables exist"); }
}
if (tab != null){
if (JacobObject.isDebugEnabled()){
JacobObject.debug("ROT: "+tab.keySet().size()+ " objects to clear in this thread " );
}
// walk the values
Iterator it;
if (USE_AUTOMATIC_GARBAGE_COLLECTION){
it = tab.keySet().iterator();
} else {
it = tab.values().iterator();
}
while (it.hasNext()) {
JacobObject o = (JacobObject) it.next();
if (o != null
// can't use this cause creates a Variant if calling SafeAray
// and we get an exceptin modifying the collection while iterating
// && o.toString() != null
){
if (JacobObject.isDebugEnabled()){
if (o instanceof SafeArray){
// SafeArray create more objects when calling toString()
// which causes a concurrent modification exception in HashMap
JacobObject.debug("ROT: removing "+o.getClass().getName());
} else {
// Variant toString() is probably always bad in here
JacobObject.debug("ROT: removing "+o.hashCode()+"->"+o.getClass().getName());
}
}
o.safeRelease();
}
// used to be an iterator.remove() but why bother when we're nuking them all anyway?
}
// empty the collection
tab.clear();
// remove the collection from rot
rot.remove(Thread.currentThread().getName());
if (JacobObject.isDebugEnabled()){
JacobObject.debug("ROT: thread table cleared and removed");
}
} else {
if (JacobObject.isDebugEnabled()){ JacobObject.debug("ROT: nothing to clear!");}
}
}
/** /**
* generates the key used to insert object into the thread's list of objects. * generates the object used to insert object into the thread's list of objects.
* @param targetMap the map we need the key for. Used to make sure we create a compatabile key * @param targetMap the map we need the key for. Used to make sure we create a compatabile key
* @param o JacobObject we need key for * @param o JacobObject we need key for
* @return some key compatabile with hashmaps * @return some compatabile with hashmaps (null for weak has map)
*/ */
protected static Object getMapKey(Map targetMap, JacobObject o){ protected static Object getMapValue( Map targetMap, JacobObject o ) {
if (targetMap instanceof WeakHashMap){ if ( targetMap instanceof WeakHashMap ) {
return o; return null;
} else { } else {
return new Integer(o.hashCode()); return o;
} }
} }
/** /**
* generates the object used to insert object into the thread's list of objects. * @deprecated the java model leave the responsibility of clearing up objects
* @param targetMap the map we need the key for. Used to make sure we create a compatabile key * to the Garbage Collector. Our programming model should not require that the
* @param o JacobObject we need key for * user specifically remove object from the thread.
* @return some compatabile with hashmaps (null for weak has map) *
*/ * This will remove an object from the ROT
protected static Object getMapValue(Map targetMap, JacobObject o){ * @param o
if (targetMap instanceof WeakHashMap){ */
return null; protected synchronized static void removeObject( JacobObject o ) {
} else { String t_name = Thread.currentThread().getName();
return o; Map tab = (Map) rot.get( t_name );
} if ( tab != null ) {
} tab.remove( getMapKey( tab, o ) );
}
o.safeRelease();
}
/** /**
* @deprecated the java model leave the responsibility of clearing up objects * adds an object to the HashMap for the current thread
* to the Garbage Collector. Our programming model should not require that the * @param o
* user specifically remove object from the thread. */
* protected synchronized static void addObject( JacobObject o ) {
* This will remove an object from the ROT Map tab = getThreadObjects( false );
* @param o if ( tab == null ) {
*/ // this thread has not been initialized as a COM thread
protected static void removeObject(JacobObject o) { // so make it part of MTA for backwards compatibility
String t_name = Thread.currentThread().getName(); ComThread.InitMTA( false );
Map tab = (Map) rot.get(t_name); tab = getThreadObjects( true );
if (tab != null) { }
tab.remove(getMapKey(tab,o)); if ( JacobObject.isDebugEnabled() ) {
} JacobObject.debug(
o.safeRelease(); "ROT: adding " + o + "->" + o.getClass().getName() +
} " table size prior to addition:" + tab.size() );
}
if ( tab != null ) {
tab.put( getMapKey( tab, o ), getMapValue( tab, o ) );
}
}
/** /**
* adds an object to the HashMap for the current thread * ROT can't be a subclass of JacobObject because of the way ROT pools are managed
* @param o * so we force a DLL load here by referncing JacobObject
*/ */
protected static void addObject(JacobObject o) { static {
Map tab = getThreadObjects(false); LibraryLoader.loadJacobLibrary();
if (tab == null) { }
// this thread has not been initialized as a COM thread
// so make it part of MTA for backwards compatibility
ComThread.InitMTA(false);
tab = getThreadObjects(true);
}
if (JacobObject.isDebugEnabled()){
JacobObject.debug(
"ROT: adding "+o+"->"+o.getClass().getName() +
" table size prior to addition:" +tab.size());}
if (tab != null) {
tab.put(getMapKey(tab,o),getMapValue(tab,o));
}
}
/**
* ROT can't be a subclass of JacobObject because of the way ROT pools are managed
* so we force a DLL load here by referncing JacobObject
*/
static {
LibraryLoader.loadJacobLibrary();
}
} }