Opened 6 years ago

Closed 4 years ago

#9709 closed defect (worksforme)

We accept way more tap cells than we process

Reported by: arma Owned by:
Priority: Medium Milestone: Tor: 0.2.6.x-final
Component: Core Tor/Tor Version:
Severity: Keywords: tor-relay 026-triaged-1
Cc: Actual Points:
Parent ID: #9657 Points:
Reviewer: Sponsor:

Description

Our fix in #7291 was meant to have us turn away onionskins that we're unlikely to get to. But in practice our #9658 patch shows that we're accepting way more than we process.

Linus briefly did a test where he cherry-picked the #9658 patch onto 0.2.4.16-rc and it was still only handling about 25% of incoming requests. His cursory analysis was that he was dropping them with the

    log_info(LD_CIRC,
             "Circuit create request is too old; canceling due to overload.");

line.

Should we be refusing these earlier, so clients can know to go elsewhere?

One possible culprit is that the main Tor thread is too busy to give cpuworker events out on time.

Child Tickets

Change History (5)

comment:1 Changed 6 years ago by cypherpunks

I believe you need to count actual number of onion added to queues, just after have_room_for_onionskin check passed. And yet need to count number of elderly requests culled by relay on overload on 5sec timeout.
With such 4 numbers (received, pended, dropped, processed) you can say what actually happens and how many onions was dropped by client's request.

comment:2 Changed 5 years ago by nickm

Milestone: Tor: 0.2.5.x-finalTor: 0.2.6.x-final

comment:3 Changed 5 years ago by arma

This ticket might become moot if #9682 ends up being good enough.

The reason we estimate so wrong about how long it will take per create cell is because of all the overhead (delay) between getting an answer from a cpuworker and realizing we should give it another question.

comment:4 Changed 5 years ago by nickm

Keywords: 026-triaged-1 added
Status: newneeds_information

We should see whether this is still happening if #9682 goes through.

comment:5 Changed 4 years ago by nickm

Resolution: worksforme
Status: needs_informationclosed

Haven't heard any complaints here for a while, and 0.2.3 is reaching the end of its shelf-life. closing...

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