[anti-censorship-team] Need to increase number of tor instances on snowflake-01 bridge, increased usage since yesterday

[Cecylia]

On 2022-09-27 10:56, Cecylia Bocovich wrote:
> On 2022-09-27 09:49, David Fifield wrote:
>> On Fri, Sep 23, 2022 at 11:01:37AM -0400, Cecylia Bocovich wrote:
>>> On 2022-09-22 11:24, David Fifield wrote:
>>>> There is increased usage of the snowflake-01 bridge since yesterday,
>>>> likely related to protests/shutdowns in Iran. The 4 load-balanced tor
>>>> instances, which recently were at about 60% CPU at the steady 
>>>> state, are
>>>> currently near 100%.
>>>>
>>>> I am planning to increase the number of instances today.
>>> It looks like we're also reaching proxy capacity again for the first 
>>> time in
>>> a while.
>>>
>>> I've attached a visualization of available proxies that are 
>>> compatible with
>>> all types of client NATs. You can see in the first image that the 
>>> number of
>>> idle proxies has gone to zero and all available proxies are being 
>>> matched.
>>> The second image shows spikes in the number of clients denied a working
>>> proxy.
>>>
>>> The depletion of this proxy pool could be due to the high amount of 
>>> mobile
>>> network usage, since these networks are likely to have complex and
>>> restrictive NAT topologies.
>> Besides recruiting more proxies, could we stretch the existing
>> unrestricted proxies further? When a proxy finds its own NAT type to be
>> unrestricted, it could increase its polling frequency and/or concurrent
>> capacity.
>
> That's a good idea.
>
> I've started working on tackling the problem from the other side[0]: 
> we have a lot of clients who may not need unrestricted proxies pulling 
> from that pool because their NAT type is unknown (see attached image).
>
> If we have these clients optimistically pull from the other pool, we 
> could reduce the load substantially. However, this change will take a 
> while to roll out because it has to be included in a Tor Browser release.
>
> Updating proxies to poll more frequently is easier to roll out quickly.
>
> [0] 
> https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/issues/40178
Oops, attaching image.
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