Prompts for GPT

User

Next, I want to support Dynamic Worker Adjustment, which dynamically adjusts the number of workers based on the length of the taskQueue. Now GoPool has a MaxWorkers attribute, perhaps adding a MinWorkers would suffice, and then support this new attribute configuration with WithMinWorkers. When the taskQueue is empty, the number of workers can be reduced; when the taskQueue exceeds a certain amount, I don't have a good idea of how to expand the workers, and I hope you can provide a reasonable solution. Please provide the relevant implementation code.

DevChat

First, we need to add a new attribute MinWorkers to the GoPool struct, and add a new option WithMinWorkers to configure this attribute. Then, we need to modify the dispatch method to implement the dynamic adjustment of the worker count.

When the length of taskQueue exceeds (MaxWorkers - MinWorkers) / 2 + MinWorkers, we can increase the worker count until it reaches MaxWorkers. When the length of taskQueue is less than MinWorkers, we can decrease the worker count until it reaches MinWorkers.

Here is the modified gopool.go file:

package gopool

import (
    "sync"
)

type Task func()

type GoPool struct {
    Workers    []*Worker
    MaxWorkers int
    MinWorkers int
    workerStack []int
    taskQueue chan Task
    lock sync.Locker
    cond *sync.Cond
}

type Option func(*GoPool)

func WithLock(lock sync.Locker) Option {
    return func(p *GoPool) {
        p.lock = lock
        p.cond = sync.NewCond(p.lock)
    }
}

func WithMinWorkers(minWorkers int) Option {
    return func(p *GoPool) {
        p.MinWorkers = minWorkers
    }
}

func NewGoPool(maxWorkers int, opts ...Option) *GoPool {
    pool := &GoPool{
        MaxWorkers: maxWorkers,
        Workers:    make([]*Worker, maxWorkers),
        workerStack: make([]int, maxWorkers),
        taskQueue: make(chan Task, 1e6),
        lock: new(sync.Mutex),
    }
    for _, opt := range opts {
        opt(pool)
    }
    if pool.cond == nil {
        pool.cond = sync.NewCond(pool.lock)
    }
    for i := 0; i < pool.MinWorkers; i++ {
        worker := newWorker()
        pool.Workers[i] = worker
        pool.workerStack[i] = i
        worker.start(pool, i)
    }
    go pool.dispatch()
    return pool
}

func (p *GoPool) AddTask(task Task) {
    p.taskQueue <- task
}

func (p *GoPool) Release() {
    close(p.taskQueue)
    p.cond.L.Lock()
    for len(p.workerStack) != p.MaxWorkers {
        p.cond.Wait()
    }
    p.cond.L.Unlock()
    for _, worker := range p.Workers {
        close(worker.TaskQueue)
    }
    p.Workers = nil
    p.workerStack = nil
}

func (p *GoPool) popWorker() int {
    p.lock.Lock()
    workerIndex := p.workerStack[len(p.workerStack)-1]
    p.workerStack = p.workerStack[:len(p.workerStack)-1]
    p.lock.Unlock()
    return workerIndex
}

func (p *GoPool) pushWorker(workerIndex int) {
    p.lock.Lock()
    p.workerStack = append(p.workerStack, workerIndex)
    p.lock.Unlock()
    p.cond.Signal()
}

func (p *GoPool) dispatch() {
    for task := range p.taskQueue {
        p.cond.L.Lock()
        for len(p.workerStack) == 0 {
            p.cond.Wait()
        }
        p.cond.L.Unlock()
        workerIndex := p.popWorker()
        p.Workers[workerIndex].TaskQueue <- task
        if len(p.taskQueue) > (p.MaxWorkers-p.MinWorkers)/2+p.MinWorkers && len(p.workerStack) < p.MaxWorkers {
            worker := newWorker()
            p.Workers = append(p.Workers, worker)
            worker.start(p, len(p.Workers)-1)
        } else if len(p.taskQueue) < p.MinWorkers && len(p.workerStack) > p.MinWorkers {
            p.Workers = p.Workers[:len(p.Workers)-1]
        }
    }
}

This solution can dynamically adjust the number of workers based on the length of the taskQueue, thereby improving the efficiency and performance of the system.

User

"github.com/daniel-hutao/spinlock"

b.ResetTimer()
for i := 0; i < b.N; i++ {
    wg.Add(taskNum)
    for num := 0; num < taskNum; num++ {
        pool.AddTask(func() {
            time.Sleep(10 * time.Millisecond)
            wg.Done()
        })
    }
}
wg.Wait()
b.StopTimer()
pool.Release()

b.ResetTimer()
for i := 0; i < b.N; i++ {
    wg.Add(taskNum)
    for num := 0; num < taskNum; num++ {
        pool.AddTask(func() {
            time.Sleep(10 * time.Millisecond)
            wg.Done()
        })
    }
}
wg.Wait()
b.StopTimer()
pool.Release()

for i := 0; i < b.N; i++ {
    wg.Add(taskNum)
    for num := 0; num < taskNum; num++ {
        go func() {
            time.Sleep(10 * time.Millisecond)
            wg.Done()
        }()
    }
}

=== RUN TestGoPoolWithMutex panic: runtime error: invalid memory address or nil pointer dereference [signal SIGSEGV: segmentation violation code=0x2 addr=0x0 pc=0x100e5e21c]

goroutine 49 [running]: github.com/devchat-ai/gopool.(*GoPool).dispatch(0x14000980000) /Users/danielhu/go/mycode/gopool/gopool.go:99 +0x9c created by github.com/devchat-ai/gopool.NewGoPool /Users/danielhu/go/mycode/gopool/gopool.go:54 +0x314 FAIL github.com/devchat-ai/gopool 1.866s

DevChat

Judging from the error message, the problem lies in the line p.Workers[workerIndex].TaskQueue <- task in the dispatch method. This may be due to our failure to properly manage the Workers slice and workerStack when dynamically adjusting the number of workers.

In our dispatch method, we try to add and remove workers in the Workers slice, but we do not update workerStack. This may cause us to try to access a non-existent worker, thus triggering a null pointer exception.

To solve this problem, we need to update workerStack at the same time when adding and removing workers. Here is the modified gopool.go file:

package gopool

import (
    "sync"
)

type Task func()

type GoPool struct {
    Workers    []*Worker
    MaxWorkers int
    MinWorkers int
    workerStack []int
    taskQueue chan Task
    lock sync.Locker
    cond *sync.Cond
}

type Option func(*GoPool)

func WithLock(lock sync.Locker) Option {
    return func(p *GoPool) {
        p.lock = lock
        p.cond = sync.NewCond(p.lock)
    }
}

func WithMinWorkers(minWorkers int) Option {
    return func(p *GoPool) {
        p.MinWorkers = minWorkers
    }
}

func NewGoPool(maxWorkers int, opts ...Option) *GoPool {
    pool := &GoPool{
        MaxWorkers: maxWorkers,
        Workers:    make([]*Worker, maxWorkers),
        workerStack: make([]int, maxWorkers),
        taskQueue: make(chan Task, 1e6),
        lock: new(sync.Mutex),
    }
    for _, opt := range opts {
        opt(pool)
    }
    if pool.cond == nil {
        pool.cond = sync.NewCond(pool.lock)
    }
    for i := 0; i < pool.MinWorkers; i++ {
        worker := newWorker()
        pool.Workers[i] = worker
        pool.workerStack[i] = i
        worker.start(pool, i)
    }
    go pool.dispatch()
    return pool
}

func (p *GoPool) AddTask(task Task) {
    p.taskQueue <- task
}

func (p *GoPool) Release() {
    close(p.taskQueue)
    p.cond.L.Lock()
    for len(p.workerStack) != p.MaxWorkers {
        p.cond.Wait()
    }
    p.cond.L.Unlock()
    for _, worker := range p.Workers {
        close(worker.TaskQueue)
    }
    p.Workers = nil
    p.workerStack = nil
}

func (p *GoPool) popWorker() int {
    p.lock.Lock()
    workerIndex := p.workerStack[len(p.workerStack)-1]
    p.workerStack = p.workerStack[:len(p.workerStack)-1]
    p.lock.Unlock()
    return workerIndex
}

func (p *GoPool) pushWorker(workerIndex int) {
    p.lock.Lock()
    p.workerStack = append(p.workerStack, workerIndex)
    p.lock.Unlock()
    p.cond.Signal()
}

func (p *GoPool) dispatch() {
    for task := range p.taskQueue {
        p.cond.L.Lock()
        for len(p.workerStack) == 0 {
            p.cond.Wait()
        }
        p.cond.L.Unlock()
        workerIndex := p.popWorker()
        p.Workers[workerIndex].TaskQueue <- task
        if len(p.taskQueue) > (p.MaxWorkers-p.MinWorkers)/2+p.MinWorkers && len(p.workerStack) < p.MaxWorkers {
            worker := newWorker()
            p.Workers = append(p.Workers, worker)
            p.workerStack = append(p.workerStack, len(p.Workers)-1)
            worker.start(p, len(p.Workers)-1)
        } else if len(p.taskQueue) < p.MinWorkers && len(p.workerStack) > p.MinWorkers {
            p.Workers = p.Workers[:len(p.Workers)-1]
            p.workerStack = p.workerStack[:len(p.workerStack)-1]
        }
    }
}

This version of the code should solve the problem you encountered.

User

You've overlooked an issue, which is that users may not configure MinWorkers, in which case NewGoPool cannot function properly. Please remember that Options are optional. When MinWorkers is not set, the default is to use maxWorkers as the Pool capacity, and the "Dynamic Worker Adjustment" feature is not enabled.

DevChat

I apologize for overlooking this issue. You're right, we need to handle the situation where the user does not configure MinWorkers. In this case, we can set MinWorkers to MaxWorkers, which would effectively disable the "Dynamic Worker Adjustment" feature.

Here is the modified gopool.go file:

package gopool

import (
    "sync"
)

type Task func()

type GoPool struct {
    Workers    []*Worker
    MaxWorkers int
    MinWorkers int
    workerStack []int
    taskQueue chan Task
    lock sync.Locker
    cond *sync.Cond
}

type Option func(*GoPool)

func WithLock(lock sync.Locker) Option {
    return func(p *GoPool) {
        p.lock = lock
        p.cond = sync.NewCond(p.lock)
    }
}

func WithMinWorkers(minWorkers int) Option {
    return func(p *GoPool) {
        p.MinWorkers = minWorkers
    }
}

func NewGoPool(maxWorkers int, opts ...Option) *GoPool {
    pool := &GoPool{
        MaxWorkers: maxWorkers,
        MinWorkers: maxWorkers, // Set MinWorkers to MaxWorkers by default
        Workers:    make([]*Worker, maxWorkers),
        workerStack: make([]int, maxWorkers),
        taskQueue: make(chan Task, 1e6),
        lock: new(sync.Mutex),
    }
    for _, opt := range opts {
        opt(pool)
    }
    if pool.cond == nil {
        pool.cond = sync.NewCond(pool.lock)
    }
    for i := 0; i < pool.MinWorkers; i++ {
        worker := newWorker()
        pool.Workers[i] = worker
        pool.workerStack[i] = i
        worker.start(pool, i)
    }
    go pool.dispatch()
    return pool
}

func (p *GoPool) AddTask(task Task) {
    p.taskQueue <- task
}

func (p *GoPool) Release() {
    close(p.taskQueue)
    p.cond.L.Lock()
    for len(p.workerStack) != p.MaxWorkers {
        p.cond.Wait()
    }
    p.cond.L.Unlock()
    for _, worker := range p.Workers {
        close(worker.TaskQueue)
    }
    p.Workers = nil
    p.workerStack = nil
}

func (p *GoPool) popWorker() int {
    p.lock.Lock()
    workerIndex := p.workerStack[len(p.workerStack)-1]
    p.workerStack = p.workerStack[:len(p.workerStack)-1]
    p.lock.Unlock()
    return workerIndex
}

func (p *GoPool) pushWorker(workerIndex int) {
    p.lock.Lock()
    p.workerStack = append(p.workerStack, workerIndex)
    p.lock.Unlock()
    p.cond.Signal()
}

func (p *GoPool) dispatch() {
    for task := range p.taskQueue {
        p.cond.L.Lock()
        for len(p.workerStack) == 0 {
            p.cond.Wait()
        }
        p.cond.L.Unlock()
        workerIndex := p.popWorker()
        p.Workers[workerIndex].TaskQueue <- task
        if len(p.taskQueue) > (p.MaxWorkers-p.MinWorkers)/2+p.MinWorkers && len(p.workerStack) < p.MaxWorkers {
            worker := newWorker()
            p.Workers = append(p.Workers, worker)
            p.workerStack = append(p.workerStack, len(p.Workers)-1)
            worker.start(p, len(p.Workers)-1)
        } else if len(p.taskQueue) < p.MinWorkers && len(p.workerStack) > p.MinWorkers {
            p.Workers = p.Workers[:len(p.Workers)-1]
            p.workerStack = p.workerStack[:len(p.workerStack)-1]
        }
    }
}

This version of the code should be able to handle the situation where the user does not configure MinWorkers.