bug: session leak

[dantengsky]

Search before asking

• I had searched in the issues and found no similar issues.

Version

b9e8582

What's Wrong?

object Session leaks

How to Reproduce?

# enable memory-profiling
cargo b  -p databend-query --features memory-profiling
# fire up databend-query
MALLOC_CONF=prof:true ./target/debug/databend-query --log-level=error

keep creating new sessions and quit, and then differ the memory

curl http://localhost:8080/debug/mem/pprof/profile > base_profile
for i in {1..1000}; do echo "select 1;" | mysql -h 127.0.0.1  -P3307 -uroot -s  -N > /dev/null; done
curl http://localhost:8080/debug/mem/pprof/profile > after_inserts
jeprof ./target/debug/databend-query --base=base_profile after_inserts --pdf > session_leak.pdf
evince session_leak.pdf

and then, got something like this, which indicates memory leaks:

session_leak.pdf

Are you willing to submit PR?

• Yes I am willing to submit a PR!

[ClSlaid]

Could it be solved by reimplementing it?
I had proposed #6306.

[zhang2014]

Could it be solved by reimplementing it?
I had proposed #6306.

It‘s a great idea to use the actor model to reimplement the session, but we may need to solve more problems, such as the complexity of the code when we need to return results(timeout, exchange channel, dead message and more). This may require some discussions and detailed design (RFC) and a lot of extra work, this almost requires the implementation of an actor system on tokio (such as akka), which is too complex for us. so let's try fixes this first.