After commit 8a0c4d5 (Merge "Repair switch to rpc stream" from Asias),
we increased the row buffer size for repair from 512KiB to 32MiB per
repair instance. We allow repairing 16 ranges (16 repair instance) in
parallel per repair request. So, a node can consume 16 * 32MiB = 512MiB
per user requested repair. In addition, the repair master node can hold
data from all the repair followers, so the memory usage on repair master
can be larger than 512MiB. We need to provide a way to limit the memory
usage.
In this patch, we limit the total memory used by repair to 10% of the
shard memory. The ranges that can be repaired in parallel is:
max_repair_ranges_in_parallel = max_repair_memory / max_repair_memory_per_range.
For example, if each shard has 4096MiB of memory, then we will have
max_repair_ranges_in_parallel = 4096MiB / 32MiB = 12.
Fixes#4675
131acc09cc