Find solution to blocking eth calls (during sync)

[farazdagi]

Problem

• eth is not responsive up until sync is done
• tested in geth --light --testnet console, no eth calls is possible if LES headers sync is in progress

Notes:

• this issue is claimed to be solved by les: fixed selectPeer deadlock, improved request distribution ethereum/go-ethereum#3519 (but it isn't)
• issue introduced in ethereum/go-ethereum@c57c54c

Resolution:

• create bug fix request by describing the issue
• briefly review if solution can be found, if so then file PR to that bug fix request

[farazdagi]

Bug fix request submitted: ethereum/go-ethereum#3639

[0xc1c4da]

related PR ethereum/go-ethereum#3660

[farazdagi]

Note to myself: ethereum/go-ethereum@682875a has updated gas estimation algorithm, so eth.estimateGas() takes slightly more time (measured in 3-5 extra seconds, per my anecdotical evidence)

[farazdagi]

We've circumvented the problem by updating all other packages, except for the LES (and we will keep it this way, up until the issue with LES blocking is properly resolved on go-ethereum side).

In the meantime, the following branches are available:

• https://github.com/status-im/status-go/commits/geth/1.5.6-stable-with-non-blocking-les
• https://github.com/status-im/status-go/commits/geth/1.5.7-stable-with-non-blocking-les
• https://github.com/status-im/status-go/commits/geth/1.5.8-stable-with-non-blocking-les
• https://github.com/status-im/status-go/commits/geth/1.5.9-stable-with-non-blocking-les

Once #117 is merged (which is based on https://github.com/status-im/status-go/commits/geth/1.5.9-stable-with-non-blocking-les) it is safe to close this issue.

[farazdagi]

• The https://github.com/status-im/status-go/commits/geth/1.5.9-stable-with-non-blocking-les has been used in release/0.9.4 - so this issue can be closed.
• Additionally, Zsolt updated his PR which has better responsiveness (yet once again, we will update LES only after I'm absolutely sure that no blocking is introduced). That will be tackled as a separate issue: LES: update to the latest version #121