encoding/json/jsontext: avoid pinning application data in pools
Previously, we put a jsontext.Encoder (or Decoder)
back into a pool with minimal reset logic.
This was semantically safe since we always did a full reset
after obtaining an Encoder/Decoder back out of the pool.
However, this meant that so long as an Encoder/Decoder was
alive in the pool, any application data referenced by the coder
would be kept alive longer than necessary.
Explicitly, clear such fields so that application data
can be more aggressively garbage collected.
Performance:
name old time/op new time/op delta
Unmarshal/Bool-32 52.0ns ± 3% 50.3ns ± 3% -3.30% (p=0.001 n=10+10)
Marshal/Bool-32 55.4ns ± 3% 54.4ns ± 2% -1.75% (p=0.006 n=10+9)
This only impacts the performance of discrete Marshal/Unmarshal calls.
For the simplest possible call (i.e., to marsha/unmarshal a bool),
there is a 1-2ns slow down. This is an appropriate slowdown
for an improvement in memory utilization.
Change-Id: I5e7d7827473773e53a9dcb3d7fe9052a75481e9f
Reviewed-on: https://go-review.googlesource.com/c/go/+/713640 Reviewed-by: Damien Neil <dneil@google.com> Reviewed-by: Johan Brandhorst-Satzkorn <johan.brandhorst@gmail.com>
TryBot-Bypass: Damien Neil <dneil@google.com> Reviewed-by: Dmitri Shuralyov <dmitshur@google.com> Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Auto-Submit: Damien Neil <dneil@google.com>