JVM container profiling from a container

In an earlier blog post, I talked about flame graphs and how I implemented those for a Scala app. Ever since I have been thinking if it would be possible to grab a flame graph from a container.

Some time ago I made that happen inspired by this post. It was not enough for me, I wanted to go deeper. I wanted also the profiler to run inside a container profiling another container. So I ended up making this

It uses the JVM async-profiler tool so not quite the same that in my previous blog post but the results are similar.

To profile another container, you can use the one-liner and replace the $CONTAINER_ID with the id of the running JVM container you want to profile, $PERF_IMAGE as the built image id of the described container and $JAVA_PID with the, you guessed it, the JVM pid inside the subject container. You also need to set a couple of runtime variables on the docker host as described in the async-profiler setup instructions.

There are a couple of drawbacks. Firstly you need to run the profiler as root. This could be altered somehow but I don't actually see this as a huge problem since the async-profiler should switch to the user the JVM belongs to anyway. This brings up the second limitation. The profiler container user needs to be the same user that the JVM process belongs to. This is a limitation in the JVM. Some further annoyances include that the JDK paths need to match in both containers and also the async profiler agent library needs to be copied to the JVM container.

Comments

I'm not a passionate developer

A family friend of mine is an airlane pilot. A dream job for most, right? As a child, I certainly thought so. Now that I can have grown-up talks with him, I have discovered a more accurate description of his profession. He says that the truth about the job is that it is boring. To me, that is not that surprising. Airplanes are cool and all, but when you are in the middle of the Atlantic sitting next to the colleague you have been talking to past five years, how stimulating can that be? When he says the job is boring, it is not a bad kind of boring. It is a very specific boring. The "boring" you would want as a passenger. Uneventful. Yet, he loves his job. According to him, an experienced pilot is most pleased when each and every tiny thing in the flight plan - goes according to plan. Passengers in the cabin of an expert pilot sit in the comfort of not even noticing who is flying. As someone employed in a field where being boring is not exactly in high demand, this sounds pro

Extracting object properties from an IFC file with IfcOpenShell

Besides the object geometry information, IFC files may contain properties for the IFC objects. The properties can be, for example, some predefined dimension information such as an object volume or a choice of material. Some of the properties are predefined in the IFC standards, but custom ones can be added. IFC files can be massive and resource-intensive to process, so in some cases, it helps to separate the object properties from the geometry data. IfcOpenShell is a toolset for processing IFC files. It is written mostly in C++ but also provides a Python interface. To read an IFC file >>> ifc_file = ifcopenshell.open("model.ifc") Fetch all objects of type IfcSlab >>> slab = ifc_file.by_type("IfcSlab")[1] Get the list of properties >>> slab.IsDefinedBy (#145075=IfcRelDefinesByType('2_fok0__fAcBZmMlQcYwie',#1,$,$,(#27,#59),#145074), #145140=IfcRelDefinesByProperties('3U2LyORgXC2f_hWf6I16C1',#1,$,$,(#27,#59),#145141), #145142

Hubristic developer

Almost half of any Finnish generation goes through a shared experience: the conscript army. An integral part of that experience is learning military slang, a set way people in the army talk. The stories told with said jargon often spread outside of the barracks. It is not uncommon to hear strangers bonding together over beers reminiscing and feeling nostalgic about freezing cold nights spent in tents. There is a similar phenomenon detectable among us coders. To be part of the coder tribe, there is at least one type of story that one must master. That is - of course - ranting about legacy codebases. "Can you believe how much of a mess the previous coders left? Hear, hear!" There is no better way to onboard a new team member than to blame some previous B-team for all the murky parts of the system at hand. This can be seen as harmless, a subject for a good meme . Rarely do we hold real grudges against "the legacy folk" and can be the best of friends in a social gather

Koodihommia

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