Fix bug in processing jobs on platforms without Docker (#1834)

* Log incoming jobs.

Log the full contents of the job protobuf to make debugging jobs easier

* Ensure that the parallel executor always uses at least one thread.

The caller may mis-calculate the number of CPUs as zero, in which case
ensure that at least one thread is spawned.

* Use runtime.NumCPU for CPU counts.

For hosts without docker, GetHostInfo() returns a blank struct which
has zero CPUs and causes downstream trouble.

---------

Co-authored-by: Paul Armstrong <psa@users.noreply.gitea.com>
Co-authored-by: Jason Song <i@wolfogre.com>

pkg/common/executor.go

@@ -3,6 +3,8 @@ package common
 import (
 	"context"
 	"fmt"
+
+	log "github.com/sirupsen/logrus"
 )
 
 // Warning that implements `error` but safe to ignore
@@ -94,6 +96,11 @@ func NewParallelExecutor(parallel int, executors ...Executor) Executor {
 		work := make(chan Executor, len(executors))
 		errs := make(chan error, len(executors))
 
+		if 1 > parallel {
+			log.Infof("Parallel tasks (%d) below minimum, setting to 1", parallel)
+			parallel = 1
+		}
+
 		for i := 0; i < parallel; i++ {
 			go func(work <-chan Executor, errs chan<- error) {
 				for executor := range work {

pkg/common/executor_test.go

@@ -100,6 +100,17 @@ func TestNewParallelExecutor(t *testing.T) {
 	assert.Equal(3, count, "should run all 3 executors")
 	assert.Equal(2, maxCount, "should run at most 2 executors in parallel")
 	assert.Nil(err)
+
+	// Reset to test running the executor with 0 parallelism
+	count = 0
+	activeCount = 0
+	maxCount = 0
+
+	errSingle := NewParallelExecutor(0, emptyWorkflow, emptyWorkflow, emptyWorkflow)(ctx)
+
+	assert.Equal(3, count, "should run all 3 executors")
+	assert.Equal(1, maxCount, "should run at most 1 executors in parallel")
+	assert.Nil(errSingle)
 }
 
 func TestNewParallelExecutorFailed(t *testing.T) {