Thanks, I used sync.Pool to allocate a byte.Buffer, and response.Body
isn't constant size in program, I find golang will grow the byte.Buffer
space against to initial space. I changed code as follows:
type SyncPool struct{ Pool sync.Pool }
func (s *SyncPool) Get(n int) []byte {
//比n大，不需要slice增长时，使用buffer pool
if b, ok := s.Pool.Get().([]byte); ok && cap(b) >= n {
return b[:n]
} else {
//miss size
s.Put(b)
return make([]byte, n)
}
}
func (s *SyncPool) Put(b []byte) {
s.Pool.Put(b)
}
const FourMB = 4 * 1024 * 1024
var pool = &SyncPool{
sync.Pool{
New: func() interface{} {
return make([]byte, FourMB)
},
},
}
On Thursday, March 26, 2020 at 12:22:01 PM UTC+8, robert engels wrote:
>
> If the pool is a sync.Pool:
>
> Any item stored in the Pool may be removed automatically at any time without
> 18 // notification. If the Pool holds the only reference when this
> happens, the 19 // item might be deallocated.
>
> So placing an object in the pool does not guarantee it won’t be collected
> - causing a future allocation.
>
> On Mar 25, 2020, at 10:22 PM, steve tang <tsg...@gmail.com <javascript:>>
> wrote:
>
> chunkCrc32Hash := crc32.NewIEEE()
> chunkBuf := bufferpool.GetInstance().Get()
> //回收buffer
> defer bufferpool.GetInstance().Put(chunkBuf)
> writer := io.MultiWriter(chunkBuf, chunkCrc32Hash)
> _, copyErr := io.Copy(writer, chunkResp.RawResponse.Body)
> if copyErr != nil && copyErr != io.EOF {
> logmgr.ErrorLogger(ctx, "fail to write chunk data to crc32 or buffer,
> req: %s, err: %s", originReq.PrettyPrint(), copyErr)
> return false, exception.OEFException(nil,
> http.StatusInternalServerError, CopyChunkError, "internal server exception")
> }
>
> In above codes, it writes chunk data to buffer pool, and the chunk data
> size is 4MB. When I used golang tool pprof to export memory pprof, there
> about 8MB space has been allocated. Could somebody help me why golang
> allocated
> memory space increases?
>
>
> <20200326-111844.png>
>
>
>
>
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> <20200326-111844.png>
>
>
>
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