JEP 240: Remove the JVM TI hprof Agent
| Owner | Staffan Larsen |
| Type | Feature |
| Scope | JDK |
| Status | Closed / Delivered |
| Release | 9 |
| Component | core-svc / tools |
| Discussion | serviceability dash dev at openjdk dot java dot net |
| Effort | XS |
| Duration | XS |
| Reviewed by | Mikael Vidstedt |
| Endorsed by | Mikael Vidstedt |
| Created | 2014/06/12 05:55 |
| Updated | 2016/06/07 23:48 |
| Issue | 8046661 |
Summary
Remove the hprof agent from the JDK.
Non-Goals
The ability to create heap dumps in the hprof format will remain.
Motivation
The useful features of the hprof agent have been superseded by better
alternatives.
Heap dumps (heap=dump)
This functionality has been superseded by the same functionality in the
JVM. Using the Diagnostic Command GC.heap_dump (jcmd <pid> GC.heap_dump) it is possible to ask the JVM to dump the heap in the
hprof file format (this is also available via jmap -dump).
Allocation profiler (heap=sites)
The Java VisualVM tool provides the same functionality, as do a number of third-party profilers.
CPU profiler (cpu=samples, cpu=times)
The CPU profiler has a couple of shortcomings which are described in some detail in http://www.brendangregg.com/blog/2014-06-09/java-cpu-sampling-using-hprof.html and elsewhere. There are other tools that provide better functionality with fewer problems. Among them are Java VisualVM and Java Flight Recorder, which are bundled with the JDK, as well as a number of third-party profilers.
Demonstration code
The hprof agent was written as demonstration code for the JVM Tool
Interface and not intended to be a production tool. The code and
documentation contain a number of statements of the following form:
This is demonstration code for the JVM TI interface and use of BCI, it is not an official product or formal part of the JDK.
Description
Stop building and shipping the hprof agent library (libhprof.so) as
part of the JDK.
Move the code to a separate project under OpenJDK. The code is still valuable as a demonstration of the capabilities of JVM TI, but it does not live up to the requirements for a shipping product.
The change should to be documented in the appropriate release notes.
Considering the extensive disclaimers already present in the
documentation, users should not be surprised that hprof is being
removed, but the documentation should be updated to point to alternative
tools.
Testing
Existing hprof agent tests will need to be removed.
