deadlock

Deadlock-Go: Dynamic Deadlock Detection in Go

What

Deadlock-Go implements Mutex and RW-Mutex drop-in replacements for sync.Mutex and sync.RWMutex with (R)Lock, (R)TryLock and (R)Unlock functionality to detect potential deadlocks.

The detector can detect potential or actually occurring recourse deadlocks which are caused by cyclic or double locking.

In some cases the detector can result in false-positiv or false-negative results. E.g., the detector is not able to detect cyclic locking in nested routines.

Only works from Go Version 1.18.

Installation

go get github.com/ErikKassubek/Deadlock-Go

Usage Examples

Example for Mutex

import "github.com/ErikKassubek/Deadlock-Go"

func main() {
	defer deadlock.FindPotentialDeadlocks()

	x := deadlock.NewLock()
	y := deadlock.NewLock()
	
	// make sure, that the program does not terminate
	// before all routines have terminated
	ch := make(chan bool, 2)

	go func() {
		x.Lock()
		y.Lock()
		y.Unlock()
		x.Unlock()
		ch <- true
	}()

	go func() {
		y.Lock()
		x.Lock()
		x.Unlock()
		y.Unlock()
		ch <- true
	}()
	<- ch
	<- ch
}

Example for RW-Mutex

import "github.com/ErikKassubek/Deadlock-Go"

func main() {
	defer deadlock.FindPotentialDeadlocks()

	x := NewRWLock()
	y := NewRWLock()

	// make sure, that the program does not terminate
	// before all routines have terminated
	ch := make(chan bool, 2)

	go func() {
		x.RLock()
		y.Lock()
		y.Unlock()
		x.Unlock()

		ch <- true
	}()

	go func() {
		y.RLock()
		x.Lock()
		x.Unlock()
		y.Unlock()

		ch <- true
	}()

	<-ch
	<-ch
}

Sample output

Cyclic Locking

POTENTIAL DEADLOCK

Initialization of locks involved in potential deadlock:

/home/***/selfWritten/deadlockGo.go 59
/home/***/selfWritten/deadlockGo.go 60
/home/***/selfWritten/deadlockGo.go 61

Calls of locks involved in potential deadlock:

Calls for lock created at: /home/***/selfWritten/deadlockGo.go:59
/home/***/selfWritten/deadlockGo.go 85
/home/***/selfWritten/deadlockGo.go 66

Calls for lock created at: /home/***/selfWritten/deadlockGo.go:60
/home/***/selfWritten/deadlockGo.go 75
/home/***/selfWritten/deadlockGo.go 67

Calls for lock created at: /home/***/selfWritten/deadlockGo.go:61
/home/***/selfWritten/deadlockGo.go 84
/home/***/selfWritten/deadlockGo.go 76

Double Locking

DEADLOCK (DOUBLE LOCKING)

Initialization of lock involved in deadlock:

/home/***/selfWritten/deadlockGo.go 205

Calls of lock involved in deadlock:

/home/***/selfWritten/deadlockGo.go 209
/home/***/selfWritten/deadlockGo.go 210

Options

The behavior of Deadlock-Go can be influenced by different options. They have to be set before the first lock was initialized.

SetActivated(enable bool): enable or disable all detections at once

SetPeriodicDetection(enable bool): enable or disable periodical detection, default: enabled

SetComprehensiveDetection(enable bool): enable or disable comprehensive detection, default: enabled

SetPeriodicDetectionTime(seconds int): set in which time intervals the periodical detection is started, default: 2s

SetCollectCallStacks(enable bool): if enabled, call-stacks for lock creation and acquisitions are collected. Otherwise only file and line information is collected, default: disabled

SetCollectSingleLevelLockInformation(enable bool): if enabled, information about single-level locks are collected, default enabled

SetDoubleLockingDetection(enable bool): if enabled, detection of double locking is active, default: enabled

Additionally the maximum numbers for the dependencies per Routine (default: 4096), the maximum number of mutexes a mutex can depend on (default: 128), the maximum number of routines (default: 1024) and the maximum length of a collected call stack in bytes (default 2048) can be set.

Acknowledgement

The detector is partially based on:

J. Zhou, S. Silvestro, H. Liu, Y. Cai und T. Liu, „UNDEAD: Detecting and preventing
deadlocks in production software“, in 2017 32nd IEEE/ACM International Conference
on Automated Software Engineering (ASE), Los Alamitos, CA, USA: IEEE Computer
Society, Nov. 2017, S. 729–740. doi: 10.1109/ASE.2017.8115684.