Steps to reproduce:
1. Create a lot time-based nodata triggers
2. Create many regular items without triggers
3. Simulate when timer process has to check time-based nodata triggers and spend some time to do that.
4. When history cache will have 1000+ values for items from these nodata triggers, history syncer misses such values, because they are locked by timer. It will not process next values till timer will free items from nodata triggers.