feat: Add hung_task_detect_count

kernel_hung.go

@@ -0,0 +1,45 @@
+// Copyright 2025 The Prometheus Authors
+// 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.
+
+//go:build !windows
+// +build !windows
+
+package procfs
+
+import (
+	"os"
+	"strconv"
+	"strings"
+)
+
+// KernelHung contains information about to the kernel's hung_task_detect_count number.
+type KernelHung struct {
+	// Indicates the total number of tasks that have been detected as hung since the system boot.
+	// This file shows up if `CONFIG_DETECT_HUNG_TASK` is enabled.
+	HungTaskDetectCount *uint64
+}
+
+// KernelHung returns values from /proc/sys/kernel/hung_task_detect_count.
+func (fs FS) KernelHung() (KernelHung, error) {
+	data, err := os.ReadFile(fs.proc.Path("sys", "kernel", "hung_task_detect_count"))
+	if err != nil {
+		return KernelHung{}, err
+	}
+	val, err := strconv.ParseUint(strings.TrimSpace(string(data)), 10, 64)
+	if err != nil {
+		return KernelHung{}, err
+	}
+	return KernelHung{
+		HungTaskDetectCount: &val,
+	}, nil
+}

kernel_hung_test.go

@@ -0,0 +1,37 @@
+// Copyright 2025 The Prometheus Authors
+// 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.
+
+//go:build !windows
+// +build !windows
+
+package procfs
+
+import (
+	"testing"
+)
+
+func TestKernelHung(t *testing.T) {
+	fs, err := NewFS(procfsFixtures)
+	if err != nil {
+		t.Fatalf("failed to access %s: %v", procfsFixtures, err)
+	}
+
+	hung, err := fs.KernelHung()
+	if err != nil {
+		t.Fatalf("failed to collect %s/sys/kernel/hung_task_detect_count: %v", procfsFixtures, err)
+	}
+
+	if *hung.HungTaskDetectCount != 6 {
+		t.Errorf("hung_task_detect_count, want %d got %d", 6, *hung.HungTaskDetectCount)
+	}
+}

testdata/fixtures.ttar

@@ -3398,6 +3398,11 @@ Mode: 755
 Directory: fixtures/proc/sys/kernel
 Mode: 755
 # ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Path: fixtures/proc/sys/kernel/hung_task_detect_count
+Lines: 1
+6
+Mode: 644
+# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 Directory: fixtures/proc/sys/kernel/random
 Mode: 755
 # ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -