hprof-slurp
hprof-slurp is a specialized JVM heap dump analyzer.
It is named after the hprof format which is used by the JDK to encode heap dumps.
The design of this tool is described in details in the following blog articles series.
Motivation
The underlying motivation is to enable the analysis of huge heap dumps which are much larger than the amount of RAM available on the host system.
hprof-slurp processes dump files in a streaming fashion in a single pass without storing intermediary results on the host.
This approach makes it possible to provide an extremely fast overview of dump files without the need to spin up expensive beefy instance.
However, it does not replace tools like Eclipse Mat and VisualVM which provide more advanced features at a different cost.
Features
- displays top
nallocated classes. - displays number of instances per class.
- displays largest instance size per class.
- display threads stack traces.
- can list all
Stringsfound.
Usage
./hprof-slurp --help
JVM heap dump hprof file analyzer
Usage: hprof-slurp [OPTIONS] --inputFile <inputFile>
Options:
-i, --inputFile <inputFile> binary hprof input file
-t, --top <top> the top results to display [default: 20]
-d, --debug debug info
-l, --listStrings list all Strings found
-h, --help Print help information
-V, --version Print version information
Example:
./hprof-slurp -i "test-heap-dumps/hprof-64.bin"
Found a total of 2.53MiB of instances allocated on the heap.
Top 20 allocated classes:
Total size | Instances | Largest | Class name
----------------------------------------------------------------------------------
1.99MiB | 436 | 634.78KiB | int[]
197.11KiB | 1991 | 16.02KiB | char[]
85.25KiB | 443 | 8.02KiB | byte[]
47.38KiB | 1516 | 32.00bytes | java.lang.String
45.42KiB | 560 | 8.02KiB | java.lang.Object[]
15.26KiB | 126 | 124.00bytes | java.lang.reflect.Field
14.77KiB | 378 | 40.00bytes | java.util.LinkedList$Node
9.94KiB | 212 | 48.00bytes | java.util.HashMap$Node
8.91KiB | 190 | 48.00bytes | java.util.LinkedList
8.42KiB | 98 | 88.00bytes | java.lang.ref.SoftReference
6.05KiB | 258 | 24.00bytes | java.lang.Integer
5.91KiB | 18 | 2.02KiB | java.util.HashMap$Node[]
5.86KiB | 150 | 40.00bytes | java.lang.StringBuilder
5.44KiB | 116 | 48.00bytes | java.util.Hashtable$Entry
5.05KiB | 38 | 136.00bytes | sun.util.locale.LocaleObjectCache$CacheEntry
5.00KiB | 40 | 128.00bytes | java.lang.ref.Finalizer
3.50KiB | 32 | 112.00bytes | java.net.URL
3.42KiB | 73 | 48.00bytes | java.io.File
3.17KiB | 12 | 776.00bytes | java.util.Hashtable$Entry[]
3.13KiB | 56 | 144.00bytes | java.lang.String[]
Performance
On modern hardware hprof-slurp can process heap dump files at around 1GB/s.
To maximize performance make sure to run on a host with at least 4 cores.
Limitations
- Tested only with
JAVA PROFILE 1.0.2&JAVA PROFILE 1.0.1formats. - Does not support dumps generated by 32 bits JVM.
Generate a heap dump
Heap dump files are sometimes generated in case of a JVM crash depending on your runtime configuration.
It can also be done manually by triggering a heap dump using jmap.
Example:
jmap -dump:format=b,file=my-hprof-file.bin <pid>
Prior art of HPROF parsing
Several projects have been very useful while researching and implementing this tool. They have provided guidance and inspiration in moments of uncertainty.