waiting to lock (a .TrueTypeFont)Īt .TrueTypeFont.getHorizontalMetrics(TrueTypeFont.java:229)Īt .GlyphTable.getGlyphData(GlyphTable.java:210)Īt .GlyphTable.getGlyph(GlyphTable.java:191) : BLOCKED (on object monitor)Īt .TrueTypeFont.getTable(TrueTypeFont.java:147) Below is the stack trace of those two threads: "APP_Thread_50_WorkerTask_pool-5-thread-6" #1899 prio=5 os_prio=0 tid=0x00007f894c405555 nid=0x44d1 waiting for monitor entry Tool pointed out the stack trace of the two threads that were in deadlock. Below is the excerpt from the fastThread report. Tool immediately pointed out that the two threads caused the deadlock. We uploaded the captured thread dump to fastThread – a thread dump analysis tool. Thus, it’s safe to capture all the prominent artifacts that are essential for troubleshooting such as: Garbage Collection log, thread dump, heap dump, netstat, iostat,… you may use 圜rash open source script, which would capture 360-degree data (GC log, 3 snapshots of thread dump, heap dump, netstat, iostat, vmstat, top, top -H,…) from your application stack within a minute and generate a bundle zip file. What you will notice is unresponsiveness from the application. Note: Most of the time, you will not know whether the actual problem in your application is deadlock or not. It contains information such as: stack trace, thread state, thread priority, … You can capture thread dump using one of the approaches given here. Thread dump is basically a snapshot of all threads that are running in your application. Thus, to analyze Deadlock, you need to capture thread dump from the application. From the above explanation you can understand that Deadlock is caused due to threads. Now let’s discuss about the Deadlock problem we faced in the application. To learn more about Deadlock basics & troubleshooting, you may refer to this blog post. The only way to recover from Deadlock is to restart the application. Similarly, once a Deadlock happens in the application, it cannot be recovered. Thus, both the trains can’t move forward. On the other hand, when Train-B is in part-4, it will be stuck waiting for part-3, which Train-A holds. Because when Train-A is in part-3 of the train track, it will be stuck waiting for part-4 of the track, which Train-B holds. Under this circumstance, Train-A and Train-B will reach a Deadlock state when they reach part-3 and part-4 of the train track. Train-A starts at part-1 and Train-B starts at Part-6 on the same train track at the same time. Let’s say there is only one train track, and this train track has six parts(part-1, part-2, part-3, part-4, part-5, part-6). Let’s look at the below practical example, which may help you to understand Deadlock better. Deadlock’s definition goes like this: “Deadlock is a situation where a set of processes are blocked because each process is holding a resource and waiting for another resource acquired by some other process.” It’s always easier to learn something new through examples and pictures. ‘Deadlock’ definition is one among them :-). Several technical definitions aren’t clear. package let’s try to understand what ‘Deadlock’ means. Let’s have a look at a simple program where I will create deadlock in java threads. Here I have written a simple program that will cause java deadlock scenario and then we will see how to analyze it. Java deadlock situation arises with at least two threads and two or more resources. Deadlock in java is a programming situation where two or more threads are blocked forever.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |