Automatic network-concurrency

[zkochan]

As of v2.22.0, pnpm uses network-concurrency 16 by default. However, in some environments, that might be too agressive, as we've seen in #1230.

pnpm should automatically decrease concurrency when fetching of a tarball fails. On the first failure, network concurrency should be decreased to 4. If a second failure happens, the network concurrency should be decreased to 1.

This logic should be the default and only used if the adjust-network-concurrency is not set or set to true.

cc @pgonzal

[zkochan]

Decreasing network concurrency might be a bad idea for pnpm server, so network concurrency should be reset after 60 seconds to the original value.

cc @etamponi

[octogonz]

Thanks for looking into this! FYI we still get occasional error reports about the "integrity checksum failed when using sha1" error (#1235), maybe a couple times per month. The --network-concurrency=1 workaround generally eliminates the symptoms, but we always have to remind people to do that.