Apply go mod tidy after local pkgs are linked

pkg/go.sum

@@ -511,6 +511,8 @@ github.com/morikuni/aec v1.0.0/go.mod h1:BbKIizmSmc5MMPqRYbxO4ZU0S0+P200+tUnFx7P
 github.com/mwitkow/go-conntrack v0.0.0-20161129095857-cc309e4a2223/go.mod h1:qRWi+5nqEBWmkhHvq77mSJWrCKwh8bxhgT7d/eI7P4U=
 github.com/mxschmitt/golang-combinations v1.0.0 h1:NFoO7CSP8MUcFlHpe1YdewKwMa15dgDbaqkVLC5DUPI=
 github.com/mxschmitt/golang-combinations v1.0.0/go.mod h1:RbMhWvfCelHR6WROvT2bVfxJvZHoEvBj71SKe+H0MYU=
+github.com/natefinch/atomic v1.0.1 h1:ZPYKxkqQOx3KZ+RsbnP/YsgvxWQPGxjC0oBt2AhwV0A=
+github.com/natefinch/atomic v1.0.1/go.mod h1:N/D/ELrljoqDyT3rZrsUmtsuzvHkeB/wWjHV22AZRbM=
 github.com/nbutton23/zxcvbn-go v0.0.0-20180912185939-ae427f1e4c1d h1:AREM5mwr4u1ORQBMvzfzBgpsctsbQikCVpvC+tX285E=
 github.com/nbutton23/zxcvbn-go v0.0.0-20180912185939-ae427f1e4c1d/go.mod h1:o96djdrsSGy3AWPyBgZMAGfxZNfgntdJG+11KU4QvbU=
 github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e h1:fD57ERR4JtEqsWbfPhv4DMiApHyliiK5xCTNVSPiaAs=

pkg/testing/integration/program.go

@@ -1933,12 +1933,6 @@ func (pt *ProgramTester) prepareGoProject(projinfo *engine.Projinfo) error {
 		}
 	}
 
-	// initial tidy to resolve dependencies
-	err = pt.runCommand("go-mod-tidy", []string{goBin, "mod", "tidy"}, cwd)
-	if err != nil {
-		return err
-	}
-
 	// link local dependencies
 	for _, pkg := range pt.opts.Dependencies {
 
@@ -1950,6 +1944,13 @@ func (pt *ProgramTester) prepareGoProject(projinfo *engine.Projinfo) error {
 			return err
 		}
 	}
+
+	// initial tidy to resolve dependencies
+	err = pt.runCommand("go-mod-tidy", []string{goBin, "mod", "tidy"}, cwd)
+	if err != nil {
+		return err
+	}
+
 	// resolve dependencies
 	err = pt.runCommand("go-mod-download", []string{goBin, "mod", "download"}, cwd)
 	if err != nil {

sdk/go.mod

@@ -22,6 +22,7 @@ require (
 	github.com/mattn/go-colorable v0.1.6 // indirect
 	github.com/mattn/go-runewidth v0.0.8 // indirect
 	github.com/mitchellh/go-ps v1.0.0
+	github.com/natefinch/atomic v1.0.1
 	github.com/nxadm/tail v1.4.8
 	github.com/opentracing/basictracer-go v1.0.0 // indirect
 	github.com/opentracing/opentracing-go v1.1.0

sdk/go.sum

@@ -139,6 +139,8 @@ github.com/mitchellh/go-ps v1.0.0 h1:i6ampVEEF4wQFF+bkYfwYgY+F/uYJDktmvLPf7qIgjc
 github.com/mitchellh/go-ps v1.0.0/go.mod h1:J4lOc8z8yJs6vUwklHw2XEIiT4z4C40KtWVN3nvg8Pg=
 github.com/mitchellh/mapstructure v1.1.2/go.mod h1:FVVH3fgwuzCH5S8UJGiWEs2h04kUh9fWfEaFds41c1Y=
 github.com/mwitkow/go-conntrack v0.0.0-20161129095857-cc309e4a2223/go.mod h1:qRWi+5nqEBWmkhHvq77mSJWrCKwh8bxhgT7d/eI7P4U=
+github.com/natefinch/atomic v1.0.1 h1:ZPYKxkqQOx3KZ+RsbnP/YsgvxWQPGxjC0oBt2AhwV0A=
+github.com/natefinch/atomic v1.0.1/go.mod h1:N/D/ELrljoqDyT3rZrsUmtsuzvHkeB/wWjHV22AZRbM=
 github.com/nxadm/tail v1.4.8 h1:nPr65rt6Y5JFSKQO7qToXr7pePgD6Gwiw05lkbyAQTE=
 github.com/nxadm/tail v1.4.8/go.mod h1:+ncqLTQzXmGhMZNUePPaPqPvBxHAIsmXswZKocGu+AU=
 github.com/oklog/ulid v1.3.1/go.mod h1:CirwcVhetQ6Lv90oh/F+FBtV6XMibvdAFo93nm5qn4U=

sdk/go/common/workspace/workspace.go

@@ -1,4 +1,4 @@
-// Copyright 2016-2018, Pulumi Corporation.
+// Copyright 2016-2021, Pulumi Corporation.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -15,6 +15,7 @@
 package workspace
 
 import (
+	"bytes"
 	// nolint: gosec
 	"crypto/sha1"
 	"encoding/hex"
@@ -25,6 +26,7 @@ import (
 	"strings"
 	"sync"
 
+	"github.com/natefinch/atomic"
 	"github.com/pkg/errors"
 
 	"github.com/pulumi/pulumi/sdk/v3/go/common/tokens"
@@ -140,7 +142,7 @@ func (pw *projectWorkspace) Save() error {
 		return err
 	}
 
-	return ioutil.WriteFile(settingsFile, b, 0600)
+	return atomic.WriteFile(settingsFile, bytes.NewReader(b))
 }
 
 func (pw *projectWorkspace) readSettings() error {

sdk/go/common/workspace/workspace_test.go

@@ -0,0 +1,61 @@
+// Copyright 2016-2021, Pulumi Corporation.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package workspace
+
+import (
+	"fmt"
+	"strings"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestWorkspaceReadWriteUnderContention(t *testing.T) {
+	n := 100
+
+	wg := &sync.WaitGroup{}
+	wg.Add(n)
+
+	var error error
+
+	for j := 0; j < n; j++ {
+		go func(i int) {
+			defer wg.Done()
+			time.Sleep(1 * time.Millisecond)
+
+			w, err := NewFrom("../../auto/test/testproj")
+			if err != nil {
+				error = err
+				return
+			}
+
+			se := w.Settings()
+
+			if se != nil {
+				se.Stack = strings.Repeat(fmt.Sprintf("abra-cadabra-i-%d", i), 1024*16)
+				err := w.Save()
+				if err != nil {
+					error = err
+					return
+				}
+			}
+		}(j)
+	}
+
+	wg.Wait()
+	assert.NoError(t, error)
+}

tests/go.mod

@@ -12,11 +12,9 @@ require (
 	github.com/blang/semver v3.5.1+incompatible
 	github.com/golang/protobuf v1.5.2
 	github.com/mattn/go-runewidth v0.0.9 // indirect
-	github.com/pkg/errors v0.9.1
 	github.com/pulumi/pulumi/pkg/v3 v3.3.0
 	github.com/pulumi/pulumi/sdk/v3 v3.3.1
 	github.com/stretchr/testify v1.7.0
-	go.opencensus.io v0.23.0 // indirect
 	google.golang.org/grpc v1.37.0
-	sourcegraph.com/sourcegraph/appdash v0.0.0-20190731080439-ebfcffb1b5c0 // indirect
+	sourcegraph.com/sourcegraph/appdash v0.0.0-20190731080439-ebfcffb1b5c0
 )