iTwinJs Error: Lock Not Held: error updating element: exclusive lock not held on element for update

[PeterJBassett]

Hello I work on developing the FutureOn - iTwin connector.
Running a connector synchronisation is failing with the error:

backend     'Lock Not Held: error updating element: exclusive lock not held on element for update (id=0xe0000000005)\n' +
backend     '    at ServerBasedLocks.checkExclusiveLock (/app/node_modules/@itwin/core-backend/lib/cjs/ServerBasedLocks.js:160:19)\n' +
backend     '    at PhysicalPartition.onUpdate (/app/node_modules/@itwin/core-backend/lib/cjs/Element.js:82:22)\n' +
backend     '    at Elements.updateElement (/app/node_modules/@itwin/core-backend/lib/cjs/IModelDb.js:1565:39)\n' +
backend     '    at FutureOnBridge.updateElement (/app/node_modules/@xvisionas/fieldtwin-itwin-connector/lib/src/FutureOnBridge.js:1267:43)\n' +
backend     '    at FutureOnBridge.getPhysicalPartition (/app/node_modules/@xvisionas/fieldtwin-itwin-connector/lib/src/FutureOnBridge.js:349:18)\n' +
backend     '    at FutureOnBridge.removePhysicalModel (/app/node_modules/@xvisionas/fieldtwin-itwin-connector/lib/src/FutureOnBridge.js:408:33)\n' +
backend     '    at FutureOnBridge.removeBathyModel (/app/node_modules/@xvisionas/fieldtwin-itwin-connector/lib/src/FutureOnBridge.js:1193:14)\n' +
backend     '    at FutureOnBridge.updateExistingData (/app/node_modules/@xvisionas/fieldtwin-itwin-connector/lib/src/FutureOnBridge.js:298:28)\n' +
backend     '    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)\n' +
backend     '    at async /app/node_modules/@itwin/connector-framework/lib/src/ConnectorRunner.js:201:13

Can you help to provide more information on what could be causing this error?

[PeterJBassett]

The connector version we are using is:

    "@itwin/connector-framework": "^2.0.5",
    "@itwin/core-backend": "^4.4.0",
    "@itwin/core-bentley": "^4.4.0",
    "@itwin/core-common": "^4.4.0",
    "@itwin/core-geometry": "^4.4.0",
    "@itwin/ecschema-metadata": "^4.4.0",
    "@itwin/imodels-access-backend": "^4.1.0",
    "@itwin/imodels-client-authoring": "^4.1.8",

[pmconne]

The error is a result of using pessimistic concurrency and failing to obtain a lock on the element you're trying to modify, before trying to modify it.

Is this a new problem? Did something change (dependency versions, your code, etc) before it began occurring? Was the physical partition you are attempting to update created by a previous run of your connector, or by something else?

Presumably your connector creates some Subject, and then puts all of the models+elements it creates under that subject's hierarchy. You should be able to use iModelDb.locks.acquireLocks to exclusively lock your root subject, which implicitly locks everything underneath that subject too.

[pmconne]

Check the be_Local tables of one iModel that works, and one that fails. Report back with which one(s) contain a "NoLocking" entry.

[PeterJBassett]

Hello @pmconne I can't do that, as I don't have access to Shell's iModels. It would need someone in Bentley to do this; who does have access.

[pmconne]

We don't have access to user's iModels either. Ask the user?

[PeterJBassett]

Hello @pmconne I have managed to track down the problem in my connector code which appears to be a timing problem acquiring the iModel lock.

So this can be closed.