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SF1603631:

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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 13:03:55 +00:00
parent 2856390f24
commit 5bcb855846
1 changed files with 21 additions and 19 deletions
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40
unittest/com/jacob/com/ROT3Test.java
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@@ -34,7 +34,7 @@ public class ROT3Test
class ROT3TestThread extends Thread class ROT3TestThread extends Thread
{ {
private java.util.List ThreadObjects; private java.util.List variansCreatedInThisThread;
private int initialRunSize = 0; private int initialRunSize = 0;
/** /**
@@ -59,34 +59,35 @@ class ROT3TestThread extends Thread
// something that keeps object references around // something that keeps object references around
// so the gc can't collect them // so the gc can't collect them
// we need to create these in the thread so they end up in the right ROT table // we need to create these in the thread so they end up in the right ROT table
ThreadObjects = new java.util.ArrayList(initialRunSize); variansCreatedInThisThread = new java.util.ArrayList(initialRunSize);
for (int i = 0; i < initialRunSize; i++) for (int i = 0; i < initialRunSize; i++)
{ {
// create the object // create the object
Variant aNewVariant = new Variant(getName() + "_" + i); Variant aNewVariant = new Variant(getName() + "_" + i);
// create a hard reference to it // create a hard reference to it
ThreadObjects.add(aNewVariant); variansCreatedInThisThread.add(aNewVariant);
} }
while (ThreadObjects.size() > 1) while (variansCreatedInThisThread.size() > 1)
{ {
String message = ""; String message = "";
message = getName()+" Workingset=" +ThreadObjects.size() message = getName()+" Workingset=" +variansCreatedInThisThread.size()
+" ROT: "+ROT.getThreadObjects(true).hashCode(); +" ROT threadObject hashCode: "+ROT.getThreadObjects(true).hashCode();
message += " before mods and gc "+ROT.getThreadObjects(true).size()+")"; message += " size before mods and gc "+ROT.getThreadObjects(true).size()+")";
// if there is an odd number of objects greater than 2 // If there are more than 10 objects in our cache then add 1/4 of that again
if (ThreadObjects.size() > 10) if (variansCreatedInThisThread.size() > 10)
{ {
message+= " ++ "; message+= " (adding) ";
for ( int i = 0 ; i < ThreadObjects.size()/4 ; i++){ // add an additional 1/4 of our current number
for ( int i = 0 ; i < variansCreatedInThisThread.size()/4 ; i++){
// add a new object // add a new object
Variant aNewVariant = new Variant(getName() + "_*" + ThreadObjects.size()); Variant aNewVariant = new Variant(getName() + "_*" + variansCreatedInThisThread.size());
ThreadObjects.add(aNewVariant); variansCreatedInThisThread.add(aNewVariant);
} }
} }
// now iterate across all the objects in our list // now iterate across 1/2 the objects in our list
message += " -- "; message += " (removing) ";
for (int i = ThreadObjects.size(); i > 0; i--) for (int i = variansCreatedInThisThread.size(); i > 0; i--)
{ {
// removing every other one? // removing every other one?
if (i % 2 == 0) if (i % 2 == 0)
@@ -95,9 +96,9 @@ class ROT3TestThread extends Thread
if (!ROT.USE_AUTOMATIC_GARBAGE_COLLECTION){ if (!ROT.USE_AUTOMATIC_GARBAGE_COLLECTION){
// uses deprecated API to set up a special situation // uses deprecated API to set up a special situation
// because this is an ROT test // because this is an ROT test
ROT.removeObject((JacobObject)ThreadObjects.get(i-1)); ROT.removeObject((JacobObject)variansCreatedInThisThread.get(i-1));
} }
ThreadObjects.remove(i-1); variansCreatedInThisThread.remove(i-1);
} }
} }
@@ -109,7 +110,8 @@ class ROT3TestThread extends Thread
} }
System.gc(); System.gc();
try { try {
Thread.sleep(2000); // vain attempt at letting the gc run
Thread.sleep(200);
} catch (InterruptedException ie){ } catch (InterruptedException ie){
} }