Debugging slow transaction submission to Azure Blockchain Service - VMSS at 100% load even after restarting with no/low transactions.

Question

I'm having a problem with slow transaction submission to the Blockchain Service, transactions appear to take several minutes to be submitted to the backing service. Only one transaction is being submitted so there is not a high load on the service, however the VMSS sits at 100% load all the time even after restarting. Is there are reason this might occur and how might I rectify it?

[Note: As we migrate from MSDN, this question has been posted by an Azure Cloud Engineer as a frequently asked question] Source: MSDN

Answer 1

The following things were contributing factors:

• I was calling the API quickly adding new transactions as fast as it would respond to queries.
• Now and again a transaction would appear to go wrong (a transaction would remain unprocessed for a while) having talked to the microsoft team, this is likely because it's nonce was out of order with previous transactions.
• Once this happened, the transactions just piled up behind it. Every time a new transaction was added whilst this was unprocessed I think it probably still used the wrong nonce to submit the next transaction
• Even once transactions were cleared, the load on VMSS stayed high.

Things that helped to work around the problem:

• I re-deployed with the newest version of Quorum
• I updated my script which loaded data such that after submitting a new contract instance, it would wait until that contract was mined into a block. This slowed the loading time for 8000 contracts from under an hour to approximately 12 hours however it now works reliably.

Source: MSDN