fix: fatal error: concurrent map read and map write on concurrency > 1

This is a revised version of 41e44f7, which doesn't make CI angry and a more straight-forward(yet smelling) implementation

Fixes #737

go.sum

@@ -8,13 +8,15 @@ dmitri.shuralyov.com/service/change v0.0.0-20181023043359-a85b471d5412/go.mod h1
 dmitri.shuralyov.com/state v0.0.0-20180228185332-28bcc343414c/go.mod h1:0PRwlb0D6DFvNNtx+9ybjezNCa8XF0xaYcETyp6rHWU=
 git.apache.org/thrift.git v0.0.0-20180902110319-2566ecd5d999/go.mod h1:fPE2ZNJGynbRyZ4dJvy6G277gSllfV2HJqblrnkyeyg=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
+github.com/Masterminds/goutils v1.1.0 h1:zukEsf/1JZwCMgHiK3GZftabmxiCw4apj3a28RPBiVg=
 github.com/Masterminds/goutils v1.1.0/go.mod h1:8cTjp+g8YejhMuvIA5y2vz3BpJxksy863GQaJW2MFNU=
 github.com/Masterminds/semver v1.4.1 h1:CaDA1wAoM3rj9sAFyyZP37LloExUzxFGYt+DqJ870JA=
 github.com/Masterminds/semver v1.4.1/go.mod h1:MB6lktGJrhw8PrUyiEoblNEGEQ+RzHPF078ddwwvV3Y=
 github.com/Masterminds/sprig v2.15.0+incompatible h1:0gSxPGWS9PAr7U2NsQ2YQg6juRDINkUyuvbb4b2Xm8w=
 github.com/Masterminds/sprig v2.15.0+incompatible/go.mod h1:y6hNFY5UBTIWBxnzTeuNhlNS5hqE0NB0E6fgfo2Br3o=
 github.com/Masterminds/sprig v2.16.0+incompatible h1:QZbMUPxRQ50EKAq3LFMnxddMu88/EUUG3qmxwtDmPsY=
 github.com/Masterminds/sprig v2.16.0+incompatible/go.mod h1:y6hNFY5UBTIWBxnzTeuNhlNS5hqE0NB0E6fgfo2Br3o=
+github.com/Masterminds/sprig v2.20.0+incompatible h1:dJTKKuUkYW3RMFdQFXPU/s6hg10RgctmTjRcbZ98Ap8=
 github.com/Masterminds/sprig v2.20.0+incompatible/go.mod h1:y6hNFY5UBTIWBxnzTeuNhlNS5hqE0NB0E6fgfo2Br3o=
 github.com/anmitsu/go-shlex v0.0.0-20161002113705-648efa622239/go.mod h1:2FmKhYUyUczH0OGQWaF5ceTx0UBShxjsH6f8oGKYe2c=
 github.com/aokoli/goutils v1.0.1 h1:7fpzNGoJ3VA8qcrm++XEE1QUe0mIwNeLa02Nwq7RDkg=

pkg/state/state.go

@@ -10,6 +10,7 @@ import (
 	"sort"
 	"strconv"
 	"strings"
+	"sync"
 
 	"github.com/roboll/helmfile/pkg/environment"
 	"github.com/roboll/helmfile/pkg/event"
@@ -248,6 +249,8 @@ func (st *HelmState) prepareSyncReleases(helm helmexec.Interface, additionalValu
 	res := []syncPrepareResult{}
 	errs := []error{}
 
+	mut := sync.Mutex{}
+
 	st.scatterGather(
 		concurrency,
 		numReleases,
@@ -272,7 +275,11 @@ func (st *HelmState) prepareSyncReleases(helm helmexec.Interface, additionalValu
 					continue
 				}
 
+				// TODO We need a long-term fix for this :)
+				// See https://github.com/roboll/helmfile/issues/737
+				mut.Lock()
 				flags, flagsErr := st.flagsForUpgrade(helm, release, workerIndex)
+				mut.Unlock()
 				if flagsErr != nil {
 					results <- syncPrepareResult{errors: []*ReleaseError{newReleaseError(release, flagsErr)}}
 					continue
@@ -683,6 +690,8 @@ func (st *HelmState) prepareDiffReleases(helm helmexec.Interface, additionalValu
 	rs := []diffPrepareResult{}
 	errs := []error{}
 
+	mut := sync.Mutex{}
+
 	st.scatterGather(
 		concurrency,
 		numReleases,
@@ -698,7 +707,11 @@ func (st *HelmState) prepareDiffReleases(helm helmexec.Interface, additionalValu
 
 				st.applyDefaultsTo(release)
 
+				// TODO We need a long-term fix for this :)
+				// See https://github.com/roboll/helmfile/issues/737
+				mut.Lock()
 				flags, err := st.flagsForDiff(helm, release, workerIndex)
+				mut.Unlock()
 				if err != nil {
 					errs = append(errs, err)
 				}