Maybe mix of two languages?

• Fun, slow parts in Perlythonubyscript?
• Important, fast parts in C?

But...

• You'll want to share code.
• Calling from C to X or X to C is slow.
• The C-X glue language is the least fun language
• You'll be lazy, and write in the fun language
• Or be lazy and waste time, and write too much stuff in C++ (like Google)

Server? Threads or events?

Threads

• C, C++, Java, ...
• Threads? Heavy. Lots of memory per thread for stacks. Be careful!Executor pool = new ScheduledThreadPoolExecutor(/* ???? guess a number */);

Events

• Perlythonubyscript: events. no choice. Callback hell.
• C, C++: libevent, etc. Callback hell.

• C#: await async await async await async await async noise

Concurrency and performance

It's really hard to pick a language!

2010. Let's try Go!

Go: 90% Perfect, 100% of the time.

Go: 90% Perfect, 100% of the time.

• Go is very good at lots of things
• High-level code when you want
• Low-level code when you want
• Start high, profile, go low-level when needed
• Static typing without too much keyboard typing

Before Go

After Go

Go's Concurrency

• Built-in! Lightweight threads, no callback hell
• Readable, top-down code
• So easy to write servers

for {  conn, err := listener.Accept()  // check err  go serve(conn)}

• Goroutine-per-request can scale

Concurrency before Go

After Go

Go is showing up for all sorts of tasks

Web frameworks

• Typically a job for scripting languages: Node.js, Python, Ruby, Perl, PHP, etc.
• net/http in the standard library
• Other http frameworks on top: gorilla, martini, Revel etc...
• No need for nginx: standard library's http server scales

Image processing

• no libpng, imagemagick, etc
• pure Go PNG, JPEG, GIF encoding & decoding in the standard library
• slower, but safer
• getting faster

Crypto

• no OpenSSL, no GnuTLS
• pure Go AES, TLS (SSL), OpenPGP, etc
• slower, but safer
• getting faster

Replacing shell scripts

• Instead of little Perl & shell scripts, I now write in Go
• os/exec package & goroutines makes subprocess management easier than shell

Camlistore

• web handlers
• using third-party web APIs
• image thumbnails: decode, resize, encode
• EXIF, ID3 parsing
• database drivers
• crypto, image decoding/resizing/encoding
• search, indexing: tight memory layout control
• WebSockets, HTTPS
• all pure Go!

Controlling flying drones

Emulators

Disassembler, linker, compiler.

• llgo compiler (Go -> LLVM IR -> ...)
• Go 1.3's disassembler
• Go 1.4's linker
• Go 1.4 or Go 1.5's compiler

Mobile

• Go runs on ARM
• minux's iOS port of Go
• Camlistore child process, goandroid

Audio synthesis

• https://github.com/nf/sigourney

Cloud infrastructure

Load balancers & servers

• YouTube's vitess: MySQL
• net/http/httputil.ReverseProxy
• dl.google.com
• etc

Raspberry Pi GPIO

What other language is used for all these?

• web apps
• scripts
• system administration
• image processing
• load balancers, servers
• crypto
• hardware

Go!

And even better...

Go built-in tools

• testing
• benchmarking
• profiling (CPU, memory, blocking)
• huge standard library
• "go get"
• godoc
• gofmt, goimports
• race detector
• static binaries

So why isn't Go perfect?

Generics

• No generics
• It sucks sometimes, but rarely
• Use maps, slices, interfaces
• Occasionally a gross interface{}
• No algorithms in stdlib
• No great proposal yet

No generics (Simon Peyton Jones: "Haskell is useless")

Data races can happen

• shared, mutable state is possible
• use channels
• be careful
• conventions and documentation help
• runtime race detector helps too$ go test -race

Code generation

• The default Go compiler often generates pretty dumb code
• Especially on ARM
• But getting better
• In Go 1.4, 1.5+: Go compiler in Go, refactor, add SSA, more optimizations

gccgo

• gccgo generates very good code
• ... but lacks escape analysis: kills performance with many small allocs + garbage
• ... GC isn't precise. Bad for 32-bit.

Compiling to JavaScript isn't yet great

• Would be nice to write frontend & backend in the same language, share code
• go/types + go/ssa enables many things:

Limited Mobile Support

• No built-in Android support (but goandroid, child processes...)
• No built-in iOS support (but unmerged port...)

Embedding Go in C/C++/Java/etc

• Can't embed Go in other languages, environments.
• e.g. Android, iOS, C/C++ programs
• problems with memory setup, GC, signals, ...
• need embedding API design
• In Go 1.4?

Shared libraries

• no shared libraries
• can't load Go code at runtime

Garbage collector

• Pauses: faster each release, good people working on it.
• Precision: heap in 1.2, most stacks in 1.3, more in 1.4.
• 4 versions of memcached: Perl, C, C++, Go

Hot stack splits

• Almost entirely fixed in Go 1.3's contiguous stacks
• Rest should be in Go 1.4.

But...

• Problems are fixable.
• It all keeps getting better with each release.

Go for everything

• Since mid-2010, I prefer 90%-perfect Go for all my hacking:

• Go is flexible, fun, readable
• Go is fast (for computers & humans)
• Go is good for working with others
• Go for everything!

Thank you