Previous value was set to avoid large cache value build
up but we can clearly see this can cause lots of GC
pauses which can lead to significant drop in performance.
Change this value to 50% and decrease the value to 25%
once the 75% cache size is used. To have a larger
window for GC pauses.
Another change is to only allow caching if a server has
more than 24GB of RAM instead of 8GB.
This change brings in changes at multiple places
- Reuse buffers at almost all locations ranging
from rpc, fs, xl, checksum etc.
- Change caching behavior to disable itself
under low memory conditions i.e < 8GB of RAM.
- Only objects cached are of size 1/10th the size
of the cache for example if 4GB is the cache size
the maximum object size which will be cached
is going to be 400MB. This change is an
optimization to cache more objects rather
than few larger objects.
- If object cache is enabled default GC
percent has been reduced to 20% in lieu
with newly found behavior of GC. If the cache
utilization reaches 75% of the maximum value
GC percent is reduced to 10% to make GC
more aggressive.
- Do not use *bytes.Buffer* due to its growth
requirements. For every allocation *bytes.Buffer*
allocates an additional buffer for its internal
purposes. This is undesirable for us, so
implemented a new cappedWriter which is capped to a
desired size, beyond this all writes rejected.
Possible fix for #3403.
Change brings in a new signVerifyReader which provides a io.Reader
compatible reader, additionally implements Verify() function.
Verify() function validates the signature present in the incoming
request. This approach is choosen to avoid complexities involved
in using io.Pipe().
Thanks to Krishna for his inputs on this.
Fixes#2058Fixes#2054Fixes#2087
The object cache implementation is XL cache, which defaults
to 8GB worth of read cache. Currently GetObject() transparently
writes to this cache upon first client read and then subsequently
serves reads from the same cache.
Currently expiration is not implemented.
