pepness commented on code in PR #6596:
URL: https://github.com/apache/netbeans/pull/6596#discussion_r1372028474
##########
enterprise/glassfish.common/src/org/netbeans/modules/glassfish/common/LogViewMgr.java:
##########
@@ -135,14 +147,11 @@ private LogViewMgr(final String uri) {
*/
public static LogViewMgr getInstance(String uri) {
LogViewMgr logViewMgr;
- synchronized (instances) {
- WeakReference<LogViewMgr> viewRef = instances.get(uri);
- logViewMgr = viewRef != null ? viewRef.get() : null;
- if(logViewMgr == null) {
- logViewMgr = new LogViewMgr(uri);
- instances.put(uri, new WeakReference<LogViewMgr>(logViewMgr));
- }
- }
+
+ logViewMgr = instances.computeIfAbsent(uri, key ->
+ new WeakReference<LogViewMgr>(new LogViewMgr(uri))
+ ).get();
Review Comment:
Will this fix the hard reference issue?
```java
public static LogViewMgr getInstance(String uri) {
LogViewMgr logViewMgr;
logViewMgr = instances.computeIfAbsent(uri, (String key) -> {
LogViewMgr _logViewMgr = new LogViewMgr(uri);
WeakReference<LogViewMgr> _viewRef = new
WeakReference<>(_logViewMgr);
return _viewRef;
}).get();
return logViewMgr;
```
Where is the race problem @matthiasblaesing? The `ConcurrentHashMap`
implementation of `computeIfAbsent` is atomic and concurrent.
[ConcurrentHashMap.computeIfAbsent](https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/util/concurrent/ConcurrentHashMap.html#computeIfAbsent(K,java.util.function.Function))
> The entire method invocation is performed atomically. The supplied
function is invoked exactly once per invocation of this method if the key is
absent, else not at all. Some attempted update operations on this map by other
threads may be blocked while computation is in progress, so the computation
should be short and simple.
This will be executed in a `synchronized` block at a Node level instead of
synchronizing the entire map.
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