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Troubleshooting Node.js
This document provides tips for troubleshooting Node.js applications when performance problems occur. It recommends logging everything, testing extensively including load testing, monitoring for errors, memory and CPU usage, and deploying automatically. When issues arise, it advises isolating the problem, measuring impacts of changes, and using tools like flamegraphs, heapdumps and the V8 profiler to identify bottlenecks like CPU-bound code, memory leaks or event loop lag.
Troubleshooting Node.js
- 1. TROUBLESHOOTING NODE.JS what to dowhen things go wrong Igor Soarez igor@yld.io @igorsoarez HassyVeldstra h@yld.io @hveldstra WDCNZ, July 2015
- 2. HELLO HELLO • YLD! •Node.js Consultancy &Training • Digital transformation for enterprise clients
- 3. FIRES Someone has toput them out
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- 5. LOG EVERYTHING Make iteasy to grep & visualise
- 6. TEST TEST TEST •Functional tests first • Good coverage for unit tests • Randomised testing & fuzz testing
- 7. MONITORING & ALERTING •Resource monitoring • CPU • Memory • I/O • Application monitoring • Errors • Real-user monitoring • Latency • Availability
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- 10. TAKEYOURTIME WHEN BUILDINGYOUR APPLICATION Tightdeadlines are the root of all evil
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- 13. LOADTESTING • You shoulddo it • Find the bottlenecks
- 14. LOADTESTING • You shoulddo it • Find the bottlenecks • Understand your system
- 15. LOADTESTING • You shoulddo it • Find the bottlenecks • Understand your system
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- 18. YOU SHOULD DOIT IN PRODUCTION
- 19. IN PRODUCTION??? I musthave heard you wrong
- 20. WHY NOT? Why —Reason 1
- 21. STAGING IS NEVERTHE SAME Why —Reason 1I
- 22. GAIN EXTRA CONFIDENCE Why— Reason 1II
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- 24. IFYOU DOTHIS • Analytics •Custom header • Cookie
- 25. IFYOU DOTHIS • Analytics •Custom header • Cookie • Let Marketing know
- 26. IFYOU DOTHIS • Analytics •Custom header • Cookie • Let Marketing know • Start outside of peak times
- 27. IFYOU DOTHIS • Analytics •Custom header • Cookie • Let Marketing know • Start outside of peak times • Start slow & ramp up
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- 30. LOADTESTINGTOOLS • JMeter • Tsung •Minigun - https://artillery.io/minigun
- 31. AFTERTHE FIRE STARTS how toapproach it
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- 33. ATTACKTHE PROBLEM 1. Isolatedtest case * 2. Measure 3. Change /Tweak / Improve 4. Goto 2 * If possible
- 34. TYPES OF ISSUES •CPU-bound code • Memory leaks • GC pressure • I/O performance • Event loop lag (Node.js)
- 35. KNOWTHETOOLS AVAILABLE • OS-level •perf • sysstat, netstat, netmon, ps, top • sysdig
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- 37. KNOWTHETOOLS AVAILABLE • Platform-specific(Node.js) • V8 profiler • find hot-path functions that cannot be optimized • trace GC activity
- 38. KNOWTHETOOLS AVAILABLE • Platform-specific(Node.js) • V8 profiler • find hot-path functions that cannot be optimized • trace GC activity • heapdump • find memory leaks
- 39. MEMORY • ps • top/ htop • Heapdumps
- 40. KNOWTHETOOLS AVAILABLE • Platform-specific(Node.js) • V8 profiler • find hot-path functions that cannot be optimized • trace GC activity • heapdump • find memory leaks • flamegraphs • see what's hot on the CPU
- 41. CPU • ps • top/ htop • Flamegraphs
- 42. KNOWTHETOOLS AVAILABLE • Platform-specific(Node.js) • V8 profiler • find hot-path functions that cannot be optimized • trace GC activity • heapdump • find memory leaks • flamegraphs • see what's hot on the CPU • node-toobusy-js • track the event loop lag
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- 45. Collected stack frames h() c()h() c() c() z() c() b() f() b() b() f() b() y() b() b() a() a() a() m() a() m() x() m() a() main() main() main() main() main() main() main() main() main()
- 46. Collapsed stack frames h() c()h() c() z() b() f() b() y() a() m() x() main()
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