Developers should use a recent version of Go for building and testing. We use the go toolchain for development, which you can get from the [Go downloads page](https://golang.org/doc/install). Geth is a Go module, and uses the [Go modules system](https://github.com/golang/go/wiki/Modules) to manage dependencies. Using `GOPATH` is not required to build go-ethereum.
### Building Executables
Switch to the go-ethereum repository root directory. All code can be built using the go tool, placing the resulting binary in `$GOPATH/bin`.
```text
go install -v ./...
```
go-ethereum exectuables can be built individually. To build just geth, use:
```text
go install -v ./cmd/geth
```
Cross compilation is not recommended, please build Geth for the host architecture.
### Testing
Testing a package:
```
go test -v ./eth
```
Running an individual test:
```
go test -v ./eth -run TestMethod
```
**Note**: here all tests with prefix _TestMethod_ will be run, so if TestMethod and TestMethod1 both exist then both tests will run.
Running benchmarks, eg.:
```
go test -v -bench . -run BenchmarkJoin
```
For more information, see the [go test flags](https://golang.org/cmd/go/#hdr-Testing_flags) documentation.
A stack trace provides a very detailed look into the current state of the geth node. It helps us to debug issues easier as it contains information about what is currently done by the node. Stack traces can be created by running `debug.stacks()` in the Geth console. If the node was started without the console command or with a script in the background, the following command can be used to dump the stack trace into a file.
Geth logs the location of the IPC endpoint on startup. It is typically under `/home/user/.ethereum/geth.ipc` or `/tmp/geth.ipc`.
`debug.stacks()` also takes an optional `filter` argument. Passing a package name or filepath to `filter` restricts the output to stack traces involcing only that package/file. For example:
```sh
debug.stacks("enode")
```
returns data that looks like:
```terminal
INFO [11-04|16:15:54.486] Expanded filter expression filter=enode expanded="`enode` in Value"
If Geth is started with the `--pprof` option, a debugging HTTP server is made available on port 6060. Navigating to <http://localhost:6060/debug/pprof> displays the heap, running routines etc. By clicking "full goroutine stack dump" a trace can be generated that is useful for debugging.
Note that if multiple instances of Geth exist, port `6060` will only work for the first instance that was launched. To generate stacktraces for other instances, they should be started up with alternative pprof ports. Ensure `stderr` is being redirected to a logfile.
