awesome limits

Preamble

Everything has limits, including software systems. When you hit these limits, bad things can happen.

You've probably hit memory and disk limits, but those aren't the only ones.

This page lists limits that, when breached, led to someone having a bad time. I tweeted about limits and got all sorts of interesting responses. This page contains some of them, with links to the tweets, which often contain more details.

Examples of limits that have been breached with ill consequences

inodes. @aegis, Alex Elman, Benjamin Stein, Thomas Attree, @dmolnar, @anotherwalther, Jinsy Oommen, Rafael Jesus, Ondrej Kokes, Peter Wang, Cadey A. Ratio, @williamsjoe, Nic Wise, ericdennis

open file descriptors / handles. Moritz Lenz, Matt McDonald, @aegis, Bruno Félix, Ken Carroll, @ehashdn, Jeff Bean, @patriotvn, Peter Wang, @asm0dio, @williamsjoe, ericdennis, Jakub Korab

processes (pids). @RuinTaughtMe, @patriotvn, Matt Tex Ackerle, @pete23com

Ports. @qudooschaudhry, Alex Hidalgo, Rafael Jesus, @williamsjoe

TCP connections. Sheeri K. Cabral, @Pluto_Berlin

Threads. @dbsmasher, David Bezley

Entropy pool. Justin Manchester, Petru Ratiu

Shebang length. @bengerman13, Anthony Sottile

Virtual memory. @shanemhansen, @williamsjoe

How fast the kernel can find an unused port to allocate a new connection. Sean Kilgore

Pod memory limits. @dastbe

Environment variable size. Glen Mailer

Java ring buffer size. Richard Tibbetts

.NET framework threadpool I/O completion port limit. Brandon Paddock

SQL Server buffer cache. Dave Poole

Concurrency limit of Java concurrent hash map. Matt McDonald

ulimit on number of processes that can be run per user. Ben Hemphill

memlock with JVM. @aegis

IOPs Arie Kachler, Jesse Noller

System time divergence. Nicolai von Neudeck

Goroutines. @beccadottex

Number of fields in an elastic search index. @bengerman13

Filename / path size limit, on Windows. @BennettElder, Peter Wang

Number of vlans in vmware vcloud director, 2015 edition. Jose manuel de arce

ipconntrack. @shanemhansen, Glen Mailer

Load balancer license connection limits. Franklin Wirtz

Wal senders. Max Knee

Kernel udp rx buffer size. @sjoeboo

Network bandwidth. @anotherwalther, Rafael Jesus

AWS API limit on number of requests made per minute when requesting new instances. Justin Manchester

Number of links to a file. @mendel

Number of files per directory. @hlieberman

VPC DNS packet limits. Rafael Jesus

Number of huge pages. @patriotvn

Connections to Oracle database. Viktor Gamov

Socket filename length limit. Anthony Sottile

Stack size. @williamsjoe

Buffer exhaustion in NICs & switches. @williamsjoe

AWS EC2 instance count limits. Nic Wise

Time Wait Assasination. John Allspaw

Semaphores. @rknayyar

Number of OS threads. AWS 2020-11-25