I am investigating JVM architecture and its working behind the scenes. I have heard a lot of times that stack stores method return types, operands, local variables and references to objects. But while reading the Oracle specification I have found the picture where drawn that stack frame has no references to o…
Tag: heap-memory
When you serialized and deserialized an Object where is saved the status of it? [closed]
Closed. This question needs details or clarity. It is not currently accepting answers. Want to improve this question? Add details and clarify the problem by editing this post. Closed 5 years ago. Improve this question I know that the objects in Java live on the Heap, but when I start to serialize the object a…
java process hangs, jvisualvm shows the process is using the all of the heap space
My java process hangs. It reads input data and parses it into Integer[] and write them into disks. jvisualvm shows the process is fully using the heap space. (java.lang.Integer and java.lang.Integer[] use 77% and 22% of the heap space respecitvely) AFAIK the java process dies showing OutOfMemory error message…
Odd heap usage pattern
I have a repeating process that: gets some data from the database builds some objects in memory, adding to a Collection writes the data from the Collection to a file All of the objects/Collections go out of scope or are set to null after each iteration. (The Collection is reused for each iteration.) Using Jav…
Clarification on run-time/compile-time and heap/stack [closed]
Closed. This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 6 years ago. Improve this question (Please excuse me if i got the title incorrect, I believe it is binding bu…
How are strings passed into methods in java (In terms of memory)
When we call methods, if you are passing in a primitive type, that value is put on the stack frame when calling the method. If you are passing in a reference type, if it’s not null, you would have already created it on the heap some where and what gets put on the stack is a reference to it. But
Calculate Xmx setting and actual heap size from Java dump
I’ve got a heap dump file (java_dump.hprof) written by a Java 7 JVM. Is it somehow possible to calculate the Xmx command line option as well as the actual heap size from this dump? Answer The dump is based on the size actually used but in a different format so it could be bigger. If the dump was trigger…
Increase the java heap space of a certain app
I have an application that I want to run it and gives it more heap memory. I run my application using this command in terminal: home/bin/hadoop jar $pathofjarfile parameter1 parameter2 but I don’t know how to allocate more heap memory when running this application? if anyone could please advise. Answer …
Why is tomcat using more and more heap space during idling?
I start tomcat using startup.bat and do nothing more with it. It is a plain vanilla installation (Version 7.0.47), as far as I know. When connecting with a JMX tool, like VisualVM I see the usage of Heap space constantly increasing. Until some garbage collection happens. And then it starts all over, again. Wh…
Memory map for Neo4j embedded
When using Neo4j in the embedded mode (Java API), one can manually set memory map settings using the following API calls (or similar): My question is: Is the mapped memory allocated out of Java heap/extended memory or from the rest of the memory available. I know that for Neo4j server the latter is correct as…