Info

Currently mongos does not return operationTime until the signing keys become available. This prevents sessions to be causally consistent as the keys are not available instantaneously. Note: returning just operationTime even if there are no keys as it does not require keys introduces issues related to a multi-shard execution without gossiping logical time. Its ok for a single RS as it does not need to gossip the clusterTime as its always matches the oplog time Suggested implementation will block in mongos initialization until keys are available if its accessing a sharded cluster 1. in initializeSharding: https://github.com/mongodb/mongo/blob/r3.5.10/src/mongo/s/server.cpp#L190 add a blocking call until keys are available: status = waitForSigningKeys(opCtx); if (!status.isOK()) { return status; } 2. implement waitForSigningKeys as (very similar to waitForShardRegistryReload) Status waitForSigningKeys(OperationContext* opCtx) { while (true) { auto stopStatus = opCtx->checkForInterruptNoAssert(); if (!stopStatus.isOK()) { return stopStatus; } try { auto logicalTimeValidator = LogicalTimeValidator::get(opCtx) if (logicalTimeValidator->shouldGossipLogicalTime()) { return Status::OK(); } sleepFor(kRetryInterval); continue; } catch (const DBException& ex) { Status status = ex.toStatus(); warning() << "Error waiting for signing keys, sleeping for 2 seconds and trying again" << causedBy(status); sleepFor(kRetryInterval); continue; } } }

Top User Comments

xgen-internal-githook commented on Mon, 31 Jul 2017 21:13:08 +0000: Author: {'email': 'misha@mongodb.com', 'username': 'mikety', 'name': 'Misha Tyulenev'} Message: SERVER-30249 wait for the signing keys to be available in mongos at startup Branch: master https://github.com/mongodb/mongo/commit/c9638cd6bcb85f6f5371ca92226d37aecf3d045b

Steps to Reproduce