opt: reduce memory pool size

[liuq19]

performance test (FSM StateMachine shrinkage)

go: added golang.org/x/text v0.3.6
name                                        old time/op    new time/op    delta
UnmarshalConcrete/CanadaGeometry_Sonic-256     925µs ±15%     933µs ±14%    ~     (p=0.841 n=5+5)
UnmarshalConcrete/CitmCatalog_Sonic-256       5.43ms ± 4%    5.65ms ± 9%    ~     (p=0.310 n=5+5)
UnmarshalConcrete/GolangSource_Sonic-256      19.1ms ± 8%    20.2ms ± 9%    ~     (p=0.151 n=5+5)
UnmarshalConcrete/StringEscaped_Sonic-256      104µs ± 8%     107µs ± 3%    ~     (p=0.421 n=5+5)
UnmarshalConcrete/StringUnicode_Sonic-256     14.1µs ±19%    12.8µs ±24%    ~     (p=0.310 n=5+5)
UnmarshalConcrete/SyntheaFhir_Sonic-256       12.9ms ± 5%    13.1ms ± 6%    ~     (p=0.841 n=5+5)
UnmarshalConcrete/TwitterStatus_Sonic-256     2.55ms ± 5%    2.60ms ± 3%    ~     (p=0.548 n=5+5)

name                                        old speed      new speed      delta
UnmarshalConcrete/CanadaGeometry_Sonic-256   296MB/s ±14%   293MB/s ±13%    ~     (p=0.841 n=5+5)
UnmarshalConcrete/CitmCatalog_Sonic-256      319MB/s ± 4%   306MB/s ± 9%    ~     (p=0.310 n=5+5)
UnmarshalConcrete/GolangSource_Sonic-256     102MB/s ± 7%    96MB/s ± 8%    ~     (p=0.151 n=5+5)
UnmarshalConcrete/StringEscaped_Sonic-256    405MB/s ± 8%   392MB/s ± 3%    ~     (p=0.421 n=5+5)
UnmarshalConcrete/StringUnicode_Sonic-256   1.30GB/s ±17%  1.45GB/s ±21%    ~     (p=0.310 n=5+5)
UnmarshalConcrete/SyntheaFhir_Sonic-256      156MB/s ± 5%   153MB/s ± 5%    ~     (p=0.841 n=5+5)
UnmarshalConcrete/TwitterStatus_Sonic-256    248MB/s ± 5%   243MB/s ± 3%    ~     (p=0.548 n=5+5)

name                                        old alloc/op   new alloc/op   delta
UnmarshalConcrete/GolangSource_Sonic-256      20.8MB ± 0%    20.7MB ± 0%  -0.46%  (p=0.008 n=5+5)
UnmarshalConcrete/SyntheaFhir_Sonic-256       10.0MB ± 0%     9.9MB ± 0%  -1.03%  (p=0.008 n=5+5)
UnmarshalConcrete/TwitterStatus_Sonic-256     1.97MB ± 1%    1.93MB ± 0%  -1.65%  (p=0.008 n=5+5)
UnmarshalConcrete/CitmCatalog_Sonic-256       4.95MB ± 1%    4.86MB ± 0%  -1.86%  (p=0.008 n=5+5)
UnmarshalConcrete/CanadaGeometry_Sonic-256     696kB ± 1%     681kB ± 0%  -2.10%  (p=0.008 n=5+5)
UnmarshalConcrete/StringEscaped_Sonic-256      101kB ± 1%      97kB ± 0%  -3.52%  (p=0.008 n=5+5)
UnmarshalConcrete/StringUnicode_Sonic-256     21.9kB ± 1%    20.9kB ± 1%  -4.34%  (p=0.008 n=5+5)

name                                        old allocs/op  new allocs/op  delta
UnmarshalConcrete/TwitterStatus_Sonic-256      1.55k ± 0%     1.56k ± 0%  +0.06%  (p=0.008 n=5+5)
UnmarshalConcrete/GolangSource_Sonic-256       13.1k ± 0%     13.1k ± 0%  +0.04%  (p=0.008 n=5+5)
UnmarshalConcrete/SyntheaFhir_Sonic-256        15.5k ± 0%     15.5k ± 0%  +0.02%  (p=0.016 n=5+4)
UnmarshalConcrete/CitmCatalog_Sonic-256        10.8k ± 0%     10.8k ± 0%  +0.01%  (p=0.016 n=5+4)
UnmarshalConcrete/CanadaGeometry_Sonic-256       567 ± 0%       567 ± 0%    ~     (all equal)
UnmarshalConcrete/StringEscaped_Sonic-256        122 ± 0%       122 ± 0%    ~     (all equal)
UnmarshalConcrete/StringUnicode_Sonic-256       4.00 ± 0%      4.00 ± 0%    ~     (all equal)

[AsterDY]

STD benchmarks (JIT stack shrinkage)

• CPU

name                           old speed      new speed       delta
pkg:github.com/bytedance/sonic/encoder goos:darwin goarch:amd64
Encoder_Generic_StdLib-16       116MB/s ± 9%    120MB/s ± 2%   +4.01%  (p=0.000 n=98+89)
Encoder_Generic_Sonic-16        369MB/s ± 9%    394MB/s ± 3%   +6.70%  (p=0.000 n=100+98)
pkg:github.com/bytedance/sonic/decoder goos:darwin goarch:amd64
Decoder_Generic_Sonic-16        170MB/s ± 5%    185MB/s ±10%   +8.57%  (p=0.000 n=84+99)
pkg:github.com/bytedance/sonic/encoder goos:darwin goarch:amd64
Encoder_Generic_Sonic_Fast-16   538MB/s ± 5%    585MB/s ± 2%   +8.72%  (p=0.000 n=85+95)
pkg:github.com/bytedance/sonic/decoder goos:darwin goarch:amd64
Decoder_Generic_StdLib-16      89.9MB/s ± 7%  101.0MB/s ± 3%  +12.36%  (p=0.000 n=92+97)
Decoder_Binding_Sonic-16        374MB/s ± 8%    428MB/s ± 2%  +14.30%  (p=0.000 n=100+94)
Decoder_Binding_Sonic_Fast-16   413MB/s ± 1%    473MB/s ± 2%  +14.42%  (p=0.019 n=2+13)
Decoder_Generic_Sonic_Fast-16   209MB/s ± 7%    244MB/s ± 4%  +16.86%  (p=0.000 n=99+96)
pkg:github.com/bytedance/sonic/encoder goos:darwin goarch:amd64
Encoder_Binding_Sonic-16       1.61GB/s ±20%   1.93GB/s ±12%  +20.15%  (p=0.000 n=100+100)
Encoder_Binding_Sonic_Fast-16  1.83GB/s ±17%   2.30GB/s ±10%  +25.49%  (p=0.000 n=84+84)

• MEM

name                           old alloc/op   new alloc/op    delta
pkg:github.com/bytedance/sonic/decoder goos:darwin goarch:amd64
Decoder_Generic_StdLib-16        50.9kB ± 0%     50.9kB ± 0%     ~     (p=0.625 n=100+99)
pkg:github.com/bytedance/sonic/encoder goos:darwin goarch:amd64
Encoder_Generic_StdLib-16        49.1kB ± 0%     49.1kB ± 0%     ~     (all equal)
pkg:github.com/bytedance/sonic/decoder goos:darwin goarch:amd64
Decoder_Generic_Sonic-16         57.7kB ± 1%     56.8kB ± 0%   -1.62%  (p=0.000 n=99+100)
Decoder_Generic_Sonic_Fast-16    49.9kB ± 1%     49.0kB ± 0%   -1.81%  (p=0.000 n=99+99)
Decoder_Binding_Sonic-16         28.2kB ± 2%     27.3kB ± 0%   -3.27%  (p=0.000 n=99+100)
Decoder_Binding_Sonic_Fast-16    25.3kB ± 1%     24.3kB ± 0%   -3.89%  (p=0.019 n=2+13)
pkg:github.com/bytedance/sonic/encoder goos:darwin goarch:amd64
Encoder_Generic_Sonic-16         12.4kB ±10%     11.2kB ± 1%   -9.57%  (p=0.000 n=98+99)
Encoder_Generic_Sonic_Fast-16    11.6kB ± 6%      9.9kB ± 1%  -14.63%  (p=0.000 n=96+100)
Encoder_Binding_Sonic-16         15.3kB ± 4%     11.9kB ± 2%  -22.58%  (p=0.000 n=99+100)
Encoder_Binding_Sonic_Fast-16    13.5kB ± 6%     10.3kB ± 2%  -23.45%  (p=0.000 n=81+93)