fix: barrier memory leak

[joway]

kitex@0.3.1

Info: [KITEX]: TPS: 221616.01, TP99: 1.15ms, TP999: 4.44ms (b=1024 Byte, c=100, n=20000000)
[KITEX@Server] CPU Usage: MIN: 180.00%, TP50: 391.00%, TP90: 393.00%, TP99: 393.82%, MAX: 394.39%, AVG:388.47%
[KITEX@Server] Mem Usage: AVG: 30 MB, MAX: 32 MB
[KITEX@Client] CPU Usage: MIN: 113.00%, TP50: 627.37%, TP90: 643.00%, TP99: 653.00%, MAX: 653.00%, AVG:582.84%
[KITEX@Client] Mem Usage: AVG: 363 MB, MAX: 806 MB

Info: [KITEX-MUX]: TPS: 305457.10, TP99: 1.04ms, TP999: 1.31ms (b=1024 Byte, c=100, n=20000000)
[KITEX-MUX@Server] CPU Usage: MIN: 178.22%, TP50: 367.63%, TP90: 368.63%, TP99: 369.37%, MAX: 369.37%, AVG:364.68%
[KITEX-MUX@Server] Mem Usage: AVG: 20 MB, MAX: 21 MB
[KITEX-MUX@Client] CPU Usage: MIN: 114.00%, TP50: 814.00%, TP90: 818.00%, TP99: 821.00%, MAX: 821.00%, AVG:722.79%
[KITEX-MUX@Client] Mem Usage: AVG: 388 MB, MAX: 811 MB

kitex@0.3.1 + netpoll@this

Info: [KITEX]: TPS: 219262.05, TP99: 1.13ms, TP999: 4.35ms (b=1024 Byte, c=100, n=20000000)
[KITEX@Server] CPU Usage: MIN: 190.00%, TP50: 390.61%, TP90: 393.00%, TP99: 394.01%, MAX: 394.18%, AVG:388.50%
[KITEX@Server] Mem Usage: AVG: 31 MB, MAX: 32 MB
[KITEX@Client] CPU Usage: MIN: 115.00%, TP50: 622.00%, TP90: 635.00%, TP99: 645.00%, MAX: 645.00%, AVG:576.21%
[KITEX@Client] Mem Usage: AVG: 359 MB, MAX: 808 MB

Info: [KITEX-MUX]: TPS: 306895.78, TP99: 1.03ms, TP999: 1.30ms (b=1024 Byte, c=100, n=20000000)
[KITEX-MUX@Server] CPU Usage: MIN: 170.00%, TP50: 367.00%, TP90: 368.00%, TP99: 368.00%, MAX: 368.00%, AVG:363.84%
[KITEX-MUX@Server] Mem Usage: AVG: 20 MB, MAX: 21 MB
[KITEX-MUX@Client] CPU Usage: MIN: 119.12%, TP50: 818.00%, TP90: 822.00%, TP99: 823.00%, MAX: 825.00%, AVG:723.53%
[KITEX-MUX@Client] Mem Usage: AVG: 388 MB, MAX: 811 MB