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https://issues.apache.org/jira/browse/NETBEANS-4696?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17189010#comment-17189010
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Jaroslav Tulach commented on NETBEANS-4696:
-------------------------------------------
The general rule to fight with deadlocks in an API is [never hold a lock when
calling foreign code|http://wiki.apidesign.org/wiki/Deadlock]. However in this
case it is not that easy to find out who's an API and who's the client. What
can help is to topologically sort and layer the modules according to their
runtime dependencies - the ones below are an API, the ones above are clients.
Then a callback from below to above which holds a lock would be problematic.
Such a callback is happening in the deadlock:
{code:java}
org.netbeans.modules.html.knockout.KOHtmlExtension.isCustomTag(KOHtmlExtension.java:302)
is being called by "lower" module:
org.netbeans.modules.html.editor.gsf.HtmlGSFParser$1.isCustomTag(HtmlGSFParser.java:109)
is being called by "lower" module:
org.netbeans.modules.html.editor.lib.api.SyntaxAnalyzerResult.doParseHtml(SyntaxAnalyzerResult.java:259)
is being called by "lower" module:
org.netbeans.modules.csl.navigation.ElementScanningTask$1.run(ElementScanningTask.java:149)
is being called by "lower" module:
org.netbeans.modules.parsing.impl.TaskProcessor.callUserTask {code}
Parsing API doesn't really hold a "lock", but it only runs in a single
dedicated thread (which is a shared, spare resource too). Can we avoid that?
Too hard, right [~tomas_zezula] & [[email protected]] & [~tzezula]? This
is a core of the indexing infrastructure. We don't want to touch it. Who else
to blame?
Let's make a rule: Whoever registers an indexer, isn't allowed to make a call
to modules "above" Parsing API.
With such rule, it is clear that {{KOHtmlExtension}} breaks it by calling into
Project UI API . Take a look at [four deadlock
conditions|http://wiki.apidesign.org/wiki/Deadlock_conditions] and select one
to break the deadlock the simplest way. This would do it:
{code:java}
---
a/webcommon/javascript2.knockout/src/org/netbeans/modules/javascript2/knockout/index/KnockoutIndex.java
+++
b/webcommon/javascript2.knockout/src/org/netbeans/modules/javascript2/knockout/index/KnockoutIndex.java
@@ -27,6 +27,8 @@
import java.util.Map;
import java.util.WeakHashMap;
import java.util.concurrent.ExecutionException;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
import java.util.logging.Logger;
import org.netbeans.api.project.Project;
import org.netbeans.api.project.ui.OpenProjects;
@@ -57,8 +59,8 @@
if (!areProjectsOpen) {
try {
// just be sure that the projects are open
- OpenProjects.getDefault().openProjects().get();
- } catch (InterruptedException | ExecutionException ex) {
+ OpenProjects.getDefault().openProjects().get(10,
TimeUnit.SECONDS);
+ } catch (InterruptedException | ExecutionException |
TimeoutException ex) {
Exceptions.printStackTrace(ex);
} finally {
areProjectsOpen = true; {code}
e.g. don't wait indefinitely. However given [Roman Svitanič's
comment|https://github.com/emilianbold/netbeans-releases/commit/30092308c4fef#diff-b6844ad6d2c225bbb1c8d6c0287d6a6cR80]
"just be sure that the projects are open" - I'd suggest to delete the whole
{{areProjectsOpen}} check. This shouldn't be here at all. If the dependency of
{{javascript2.knockout}} module on Project UI API can be removed, then even
better!
> NetBeans 12.1-beta1 sometimes hangs on open
> -------------------------------------------
>
> Key: NETBEANS-4696
> URL: https://issues.apache.org/jira/browse/NETBEANS-4696
> Project: NetBeans
> Issue Type: Bug
> Components: ide - Performance
> Affects Versions: 12.1
> Environment: Linux (Debian "Buster")
> OpenJDK Runtime Environment AdoptOpenJDK (build 11.0.7+10)
> Reporter: Glenn Holmer
> Priority: Major
> Attachments: 12.1-vc1-thread-dump-orac.txt,
> nb12.1-beta1-thread-dump.png, nb12.1-beta1-thread-dump.txt,
> netbeans-12.1-thread-dump.txt
>
>
>
> NetBeans sometimes hangs on startup; the symptom is a stalled "Opening
> Projects" progress bar. I haven't been able to find a repro case, but I'm
> attaching a thread dump (from VisualVM) and screen shot.
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