Author: sebb
Date: Sat Jan 17 11:30:31 2015
New Revision: 1652582
URL: http://svn.apache.org/r1652582
Log:
BCEL-186 Performance degradation with the UTF8 cache
Tidy up and simplify caching code in case it can be made performant
Might still be useful as a way of saving memory in some cases
Modified:
commons/proper/bcel/trunk/src/main/java/org/apache/bcel/classfile/ConstantUtf8.java
Modified:
commons/proper/bcel/trunk/src/main/java/org/apache/bcel/classfile/ConstantUtf8.java
URL:
http://svn.apache.org/viewvc/commons/proper/bcel/trunk/src/main/java/org/apache/bcel/classfile/ConstantUtf8.java?rev=1652582&r1=1652581&r2=1652582&view=diff
==============================================================================
---
commons/proper/bcel/trunk/src/main/java/org/apache/bcel/classfile/ConstantUtf8.java
(original)
+++
commons/proper/bcel/trunk/src/main/java/org/apache/bcel/classfile/ConstantUtf8.java
Sat Jan 17 11:30:31 2015
@@ -40,53 +40,71 @@ public final class ConstantUtf8 extends
private static final long serialVersionUID = -8709101585611518985L;
private final String bytes;
- private static final int MAX_CACHE_ENTRIES = 20000;
- private static final int INITIAL_CACHE_CAPACITY =
(int)(MAX_CACHE_ENTRIES/0.75);
- private static HashMap<String, ConstantUtf8> cache;
- private static int considered = 0;
- private static int hits = 0;
- private static int skipped = 0;
- private static int created = 0;
- static final boolean BCEL_STATISTICS =
Boolean.getBoolean("bcel.statistics");
- static final boolean BCEL_DONT_CACHE =
Boolean.getBoolean("bcel.dontCache");
+ private static volatile int considered = 0;
+ private static volatile int hits = 0;
+ private static volatile int skipped = 0;
+ private static volatile int created = 0;
+
+ // Set the size to 0 or below to skip caching entirely
+ private static final int MAX_CACHED_SIZE =
Integer.getInteger("bcel.maxcached.size");
+ private static final boolean BCEL_STATISTICS =
Boolean.getBoolean("bcel.statistics");
+
+
+ private static class CACHE_HOLDER {
+
+ private static final int MAX_CACHE_ENTRIES = 20000;
+ private static final int INITIAL_CACHE_CAPACITY =
(int)(MAX_CACHE_ENTRIES/0.75);
+
+ private static final HashMap<String, ConstantUtf8> CACHE =
+ new LinkedHashMap<String,
ConstantUtf8>(INITIAL_CACHE_CAPACITY, 0.75f, true) {
+ private static final long serialVersionUID = -8506975356158971766L;
+
+ @Override
+ protected boolean removeEldestEntry(Map.Entry<String,
ConstantUtf8> eldest) {
+ return size() > MAX_CACHE_ENTRIES;
+ }
+ };
+
+ }
+
+ // for accesss by test code
+ static void printStats() {
+ System.err.println("Cache hit " + hits + "/" + considered +", " +
skipped + " skipped");
+ System.err.println("Total of " + created + " ConstantUtf8 objects
created");
+ }
+
+ // for accesss by test code
+ static void clearStats() {
+ hits = considered = skipped = created = 0;
+ }
static {
if (BCEL_STATISTICS) {
Runtime.getRuntime().addShutdownHook(new Thread() {
@Override
public void run() {
- System.err.println("Cache hit " + hits + "/" + considered
+", "
- + skipped + " skipped");
- System.err.println("Total of " + created + " ConstantUtf8
objects created");
+ printStats();
}
});
}
}
- public static synchronized ConstantUtf8 getCachedInstance(String s) {
- if (BCEL_DONT_CACHE || s.length() > 200) {
+ public static ConstantUtf8 getCachedInstance(String s) {
+ if (s.length() > MAX_CACHED_SIZE) {
skipped++;
return new ConstantUtf8(s);
}
considered++;
- if (cache == null) {
- cache = new LinkedHashMap<String,
ConstantUtf8>(INITIAL_CACHE_CAPACITY, 0.75f, true) {
- private static final long serialVersionUID =
-8506975356158971766L;
-
- @Override
- protected boolean removeEldestEntry(Map.Entry<String,
ConstantUtf8> eldest) {
- return size() > MAX_CACHE_ENTRIES;
+ synchronized (ConstantUtf8.class) { // might be better with a specific
lock object
+ ConstantUtf8 result = CACHE_HOLDER.CACHE.get(s);
+ if (result != null) {
+ hits++;
+ return result;
}
- };
+ result = new ConstantUtf8(s);
+ CACHE_HOLDER.CACHE.put(s, result);
+ return result;
}
- ConstantUtf8 result = cache.get(s);
- if (result != null) {
- hits++;
- return result;
- }
- result = new ConstantUtf8(s);
- cache.put(s, result);
- return result;
}
public static ConstantUtf8 getInstance(String s) {
