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speedb-io / speedb

A RocksDB compliant high performance scalable embedded key-value store
https://www.speedb.io/
Apache License 2.0
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Allocate memtable from the Arena #749

Open Guyme opened 10 months ago

Guyme commented 10 months ago

Currently the speedb memtable does not allocate memory from the Arena.

ayulas commented 10 months ago

its not true! the memtable allocates the data from the arena! the bucket is not allocates from the arena but i dont think it should

udi-speedb commented 10 months ago

@ofriedma - could you please give actual stats about the total memory allocations of our memtable, and show how much if from the arena and how much is not?

ofriedma commented 10 months ago

LOG-hashspdb-memory.txt LOG-skiplist-memory.txt

At least from this log, there is a gap between the skiplist and our spdb hash, some memory is not transparent through the arena stats or the BlockFetcher stats in the hash spdb.

udi-speedb commented 10 months ago

LOG-hashspdb-memory.txt LOG-skiplist-memory.txt

At least from this log, there is a gap between the skiplist and our spdb hash, some memory is not transparent through the arena stats or the BlockFetcher stats in the hash spdb.

@ofriedma - Thanks. Could you please summarise the highlights of your findings here. Thanks

Guyme commented 10 months ago

First fix the memtable memory consumption - #618 Then add to the Arena (this ticket)

ofriedma commented 10 months ago

Summary from the logs:

SkipList memory information:

2023/11/08-16:23:32.972665 33053 [/db_impl/db_impl.cc:1138] --- Malloc STATS count=11986 memory=3292MB total=28017343 2023/11/08-16:23:32.972668 33053 [/db_impl/db_impl.cc:1141] Arena Stats: Arena total: 3402655080 2023/11/08-16:23:32.972789 33053 [/db_impl/db_impl.cc:1173] Total CacheAllocationUsage: 32654944

Hash spdb:

2023/11/08-16:35:58.474413 33460 [/db_impl/db_impl.cc:1138] --- Malloc STATS count=30610 memory=6040MB total=286460724 2023/11/08-16:35:58.474419 33460 [/db_impl/db_impl.cc:1141] Arena Stats: Arena total: 3592552848 2023/11/08-16:35:58.474950 33460 [/db_impl/db_impl.cc:1173] Total CacheAllocationUsage: 292628424

We can see there are differences between the allocations, higher memory consumption on hash spdb, that is not allocated through the arena.