In commit `488e2b00bf881b97bcc8e4bbe304845ff1d79a03`, we've refactored the block the connection on bandwidth logic and *one* typo got in, probably bad copy paste: ``` void connection_write_bw_exhausted(connection_t *conn, bool is_global_bw) { (void)is_global_bw; conn->write_blocked_on_bw = 1; connection_stop_reading(conn); reenable_blocked_connection_schedule(); } ``` Notice the `connection_stop_reading()` call where it should be a _stop writing_ ... This has the really bad side effect of making tor stop reading on the socket if the write limit is reached, and because `read_blocked_on_bw` is not set to 1, it is never reenabled through our mainloop callback. This fix is *critical* else bytes accumulate in the kernel TCP buffers which can lead to OOM but also lost of connectivity with >= 0.3.4.x relays. One way to accumulate is the keepalive cell that bypasses KIST scheduler so tor sends it regardless if the kernel thinks it is OK. I'll open a ticket for this which is another problem. This is most likely fixing legacy/trac#27813. Appeared in 0.3.4.1-alpha.