hugolib: Prevent parallel server rebuilds

There have been reports about infrequent paginator crashes when running the Hugo server since 0.55.0.

The reason have been narrowed down to that of parallel rebuilds.

This isn't a new thing, but the changes in 0.55.0 made it extra important to serialize the page initialization.

This commit fixes that by protecting the `Build` method with a lock when running in server mode.

Fixes #5885
Fixes #5968

diff --git a/hugolib/hugo_sites.go b/hugolib/hugo_sites.go
index 6f95dbb12c3f2b280215d4d3c1998437ab7968f5..5be4ec02b75b324ed80064a6317b3e0a4ba97a3b 100644 (file)
--- a/hugolib/hugo_sites.go
+++ b/hugolib/hugo_sites.go
@@ -62,6 +62,9 @@ type HugoSites struct {
        // If this is running in the dev server.
        running bool
 
+       // Serializes rebuilds when server is running.
+       runningMu sync.Mutex
+
        // Render output formats for all sites.
        renderFormats output.Formats
 

diff --git a/hugolib/hugo_sites_build.go b/hugolib/hugo_sites_build.go
index d748a0169dd815ace68aed471317cd14971c80ba..7f725def2f952d3f17223ded7bd117177b2b1371 100644 (file)
--- a/hugolib/hugo_sites_build.go
+++ b/hugolib/hugo_sites_build.go
@@ -31,6 +31,12 @@ import (
 // Build builds all sites. If filesystem events are provided,
 // this is considered to be a potential partial rebuild.
 func (h *HugoSites) Build(config BuildCfg, events ...fsnotify.Event) error {
+       if h.running {
+               // Make sure we don't trigger rebuilds in parallel.
+               h.runningMu.Lock()
+               defer h.runningMu.Unlock()
+       }
+
        ctx, task := trace.NewTask(context.Background(), "Build")
        defer task.End()