uobjnew(8)

✨ uobjnew(8) — System Manager's Manual ✨

uobjnew, cobjnew, javaobjnew, rubyobjnew, tclobjnew — summarize object allocations in high-level languages 🦋

🌸 NAME 🌸

okay so the name section is basically the family tree 🧚 these are all the same tool wearing different outfits, one per language: uobjnew, cobjnew, javaobjnew, rubyobjnew, and tclobjnew. they all count object allocations in high-level languages 💅

💖 SYNOPSIS 💖

cobjnew [-h] [-C TOP_COUNT] [-S TOP_SIZE] [-v] pid [interval]
javaobjnew [-h] [-C TOP_COUNT] [-S TOP_SIZE] [-v] pid [interval]
rubyobjnew [-h] [-C TOP_COUNT] [-S TOP_SIZE] [-v] pid [interval]
tclobjnew [-h] [-C TOP_COUNT] [-S TOP_SIZE] [-v] pid [interval]
uobjnew [-h] [-C TOP_COUNT] [-S TOP_SIZE] [-v] [-l {c,java,ruby,tcl}]
pid [interval]

🎀 DESCRIPTION 🎀

bestie, this one is so good 😭 uobjnew watches object allocations in high-level languages (and yes, that includes malloc 🙈) and then gives you a summary of the most-allocated types, ranked by how many objects there are or how many bytes they eat.

the tool leans on USDT probes that are baked into lots of high-level languages, like C, Java, Ruby, and Tcl. so your runtime has to be instrumented with those probes first 🔥 sometimes that means building from source with a USDT-specific flag, like --enable-dtrace or --with-dtrace. and for Java, the process has to be launched with the -XX:+ExtendedDTraceProbes flag, or it's a no-go 💀

also, this uses BPF, so only the root user can run it. sorry not sorry 👑

🧚 REQUIREMENTS 🧚

you'll need CONFIG_BPF and bcc 🌈

✨ OPTIONS ✨

• -C TOP_COUNT — show the top object types, sorted by how many instances there are 🍓
• -S TOP_SIZE — show the top object types, sorted by size instead 💜
• -v — dump the BPF program that gets generated, for debugging 🔍
• {c,java,ruby,tcl} — the language you want to trace 🦋
• pid — the process ID you're tracing 🫶
• interval — wait this many seconds, then print the summary and bounce. if you skip it, the tool just keeps going until you hit Ctrl+C ⭐

🌷 EXAMPLES 🌷

trace object allocations in a Ruby process:

# uobjnew ruby 148

trace allocations from malloc and print the top 10 by total size (this one is giving main character energy 👑):

# uobjnew -S 10 c 1788

💅 FIELDS 💅

• TYPE — the object type being allocated. for C (malloc), this is the block size 🎀
• ALLOCS — how many objects got allocated 🧁
• BYTES — how many bytes got allocated 🌈

🔥 OVERHEAD 🔥

⚠️ okay this part is serious. object allocation events happen constantly, so this tool can add a real amount of overhead. use it with caution, and test it before you even think about running it in production 🙈

that said, even thousands of allocations per second should give you reasonable overhead when you're debugging a problem, so it's not a total disaster 🫶

🦋 SOURCE 🦋

this comes from bcc 💖

🔗 https://github.com/iovisor/bcc

also check the bcc distribution for a companion _example.txt file. it has example usage, output, and commentary for this tool, and it's honestly a vibe 📚

🌈 OS 🌈

Linux 🐧

🙈 STABILITY 🙈

unstable, still in development. so it's not fully baked yet, babe 🧪

👑 AUTHOR 👑

written by Sasha Goldshtein ✨

💜 SEE ALSO 💜

ustat(8), ugc(8), memleak(8) — iykyk 🫶

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the whole page is from USER COMMANDS, dated 2018-10-09, and it's the manual for uobjnew(8), sourced from bcc. go forth and count your allocations, queen 👑💖🦋✨