fix latency

Signed-off-by: Robert Landers <landers.robert@gmail.com>

frankenphp.go

@@ -35,8 +35,8 @@ import (
 	"syscall"
 	"time"
 	"unsafe"
-	// debug on Linux
-	//_ "github.com/ianlancetaylor/cgosymbolizer"
+
+	"golang.org/x/sync/semaphore"
 )
 
 type contextKeyStruct struct{}
@@ -307,9 +307,11 @@ func Init(options ...Option) error {
 		return err
 	}
 
-	regularRequestChan = make(chan contextHolder, opt.numThreads-workerThreadCount)
-	regularThreads = make([]*phpThread, 0, opt.numThreads-workerThreadCount)
-	for i := 0; i < opt.numThreads-workerThreadCount; i++ {
+	numRegularThreads := opt.numThreads - workerThreadCount
+	regularRequestChan = make(chan contextHolder)
+	regularSemaphore = semaphore.NewWeighted(int64(numRegularThreads))
+	regularThreads = make([]*phpThread, 0, numRegularThreads)
+	for i := 0; i < numRegularThreads; i++ {
 		convertToRegularThread(getInactivePHPThread())
 	}
 

go.mod

@@ -13,6 +13,7 @@ require (
 	go.uber.org/zap v1.27.0
 	go.uber.org/zap/exp v0.3.0
 	golang.org/x/net v0.47.0
+	golang.org/x/sync v0.18.0
 )
 
 require (

threadregular.go

@@ -2,7 +2,10 @@ package frankenphp
 
 import (
 	"context"
+	"runtime"
 	"sync"
+
+	"golang.org/x/sync/semaphore"
 )
 
 // representation of a non-worker PHP thread
@@ -19,6 +22,7 @@ var (
 	regularThreads     []*phpThread
 	regularThreadMu    = &sync.RWMutex{}
 	regularRequestChan chan contextHolder
+	regularSemaphore   *semaphore.Weighted // FIFO admission control
 )
 
 func convertToRegularThread(thread *phpThread) {
@@ -100,6 +104,16 @@ func (handler *regularThread) afterRequest() {
 func handleRequestWithRegularPHPThreads(ch contextHolder) error {
 	metrics.StartRequest()
 
+	// yield to ensure this goroutine doesn't end up on the same P queue
+	runtime.Gosched()
+
+	// Enforce FIFO ordering of requests
+	if err := regularSemaphore.Acquire(ch.ctx, 1); err != nil {
+		ch.frankenPHPContext.reject(err)
+		return err
+	}
+	defer regularSemaphore.Release(1)
+
 	select {
 	case regularRequestChan <- ch:
 		// a thread was available to handle the request immediately