for i := 0; i < 100; i++ {
				x /= x + 1
			}
		}
	})
}

func BenchmarkWithTimeout(b *testing.B) {
	for concurrency := 40; concurrency <= 4e5; concurrency *= 100 {
		name := fmt.Sprintf("concurrency=%d", concurrency)
		b.Run(name, func(b *testing.B) {
			benchmarkWithTimeout(b, concurrency)
		})
	}
}

func benchmarkWithTimeout(b *testing.B, concurrentContexts int) {
	gomaxprocs := runtime.GOMAXPROCS(0)

env GO111MODULE=on

# Concurrent builds should succeed, even if they need to download modules.
go get ./x ./y
go build ./x &
go build ./y
wait

# Concurrent builds should update go.sum to the union of the hashes for the
# modules they read.
cmp go.sum go.sum.want

-- go.mod --
module golang.org/issue/26794

require (
	golang.org/x/text v0.3.0
	rsc.io/sampler v1.0.0
)
-- x/x.go --
package x

}

// A sequencer performs concurrent tasks that may write output, but emits that
// output in a deterministic order.
type sequencer struct {
	maxWeight int64
	sem       *semaphore.Weighted   // weighted by input bytes (an approximate proxy for memory overhead)
	prev      <-chan *reporterState // 1-buffered
}

// newSequencer returns a sequencer that allows concurrent tasks up to maxWeight

// and both are correct.
//
// The next example uses a go statement and has a similar problem [<go1.22].
// In addition, it has a data race because the loop updates v
// concurrent with the goroutines accessing it.
//
//	for _, v := range elem {
//	    go func() {
//	        use(v)  // incorrect, and a data race
//	    }()
//	}
//

	// if any download failed due to a TooNewError, we switch toolchains and try
	// again. Any downloads that already succeeded will still be in cache.
	// That won't give optimal concurrency (we'll do two batches of concurrent
	// downloads instead of all in one batch), and it might add a little overhead
	// to look up the downloads from the first batch in the module cache when

	b.lastRuneSize = -1
	return nil
}

// Buffered returns the number of bytes that can be read from the current buffer.
func (b *Reader) Buffered() int { return b.w - b.r }

// ReadSlice reads until the first occurrence of delim in the input,
// returning a slice pointing at the bytes in the buffer.
// The bytes stop being valid at the next read.
// If ReadSlice encounters an error before finding a delimiter,

stdout 'Don''t communicate by sharing memory'

# Modules can be replaced by local packages.
cp go.mod.orig go.mod
go mod edit -replace=rsc.io/quote/v3=./local/rsc.io/quote/v3
go build -o a2.exe .
exec ./a2.exe
stdout 'Concurrency is not parallelism.'

# The module path of the replacement doesn't need to match.
# (For example, it could be a long-running fork with its own import path.)
cp go.mod.orig go.mod

// writing to a single underlying output stream w.
// As long as the underlying output w can handle concurrent writes
// from multiple goroutines, the result will be a JSON stream
// describing the relative ordering of execution in all the concurrent tests.
//
// The mode flag adjusts the behavior of the converter.
// Passing ModeTime includes event timestamps and elapsed times.
//

			// we need to make sure we wake up exactly this one.
			// That means that we need to Broadcast to all of the goroutines,
			// which will wake them all up.
			//
			// If there are N concurrent calls to waitOnCond, each of the goroutines
			// will spuriously wake up O(N) other goroutines that aren't ready yet,
			// so this will cause the overall CPU cost to be O(N²).
			cond.Broadcast()
		})
		defer stopf()

// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

// Compute Fibonacci numbers with two goroutines
// that pass integers back and forth.  No actual
// concurrency, just threads and synchronization
// and foreign code on multiple pthreads.

package main

import (
	big "."
	"runtime"
)

func fibber(c chan *big.Int, out chan string, n int64) {