Lower the maximum block range in getLogs requests to 1000

beacon_chain/eth1/eth1_monitor.nim

@@ -57,7 +57,29 @@ contract(DepositContract):
 const
   hasDepositRootChecks = defined(has_deposit_root_checks)
 
-  targetBlocksPerLogsRequest = 5000'u64  # This is roughly a day of Eth1 blocks
+  targetBlocksPerLogsRequest = 1000'u64
+    # TODO
+    #
+    # This is currently set to 1000, because this was the default maximum
+    # value in Besu circa our 22.3.0 release. Previously, we've used 5000,
+    # but this was effectively forcing the fallback logic in `syncBlockRange`
+    # to always execute multiple requests before getting a successful response.
+    #
+    # Besu have raised this default to 5000 in https://github.com/hyperledger/besu/pull/5209
+    # which is expected to ship in their next release.
+    #
+    # Full deposits sync time with various values for this parameter:
+    #
+    # Blocks per request | Geth running on the same host | Geth running on a more distant host
+    # ----------------------------------------------------------------------------------------
+    # 1000               |                      11m 20s  |                                 22m
+    # 5000               |                       5m 20s  |                             15m 40s
+    # 100000             |                       4m 10s  |                          not tested
+    #
+    # The number of requests scales linearly with the parameter value as you would expect.
+    #
+    # These results suggest that it would be reasonable for us to get back to 5000 once the
+    # Besu release is well-spread within their userbase.
 
   # Engine API timeouts
   engineApiConnectionTimeout = 5.seconds  # How much we wait before giving up connecting to the Engine API