Currently, when object-server serves GET request and DiskFile
reader iterate over disk file chunks, there is no explicit
eventlet sleep called. When network outpace the slow disk IO,
it's possible one large and slow GET request could cause
eventlet hub not to schedule any other green threads for a
long period of time. To improve this, this patch add a
configurable sleep parameter into DiskFile reader, which
is 'cooperative_period' with a default value of 0 (disabled).
Co-Authored-By: Clay Gerrard <clay.gerrard@gmail.com>
Change-Id: I80b04bad0601b6cd6caef35498f89d4ba70a4fd4
d5877179a5