EDIT

One single CDMLight export of the euromed database produces 49173 lines of logging like :

[euromed] 2019-07-31 12:04:20,009 INFO [Thread-5721] [eu.etaxonomy.cdm.common.monitor.DefaultProgressMonitor] - 99.87431% done (Completed Task: Writing partition 477/478)
[euromed] 2019-07-31 12:04:20,052 INFO [Thread-5721] [eu.etaxonomy.cdm.common.monitor.DefaultProgressMonitor] - 99.8757% done (Completed Task: Writing partition 477/478)
[euromed] 2019-07-31 12:04:20,186 INFO [Thread-5721] [eu.etaxonomy.cdm.common.monitor.DefaultProgressMonitor] - 99.8771% done (Completed Task: Writing partition 477/478)
[euromed] 2019-07-31 12:04:20,239 INFO [Thread-5721] [eu.etaxonomy.cdm.common.monitor.DefaultProgressMonitor] - 99.8785% done (Completed Task: Writing partition 477/478)
[euromed] 2019-07-31 12:04:20,298 INFO [Thread-5721] [eu.etaxonomy.cdm.common.monitor.DefaultProgressMonitor] - 99.87989% done (Completed Task: Writing partition 477/478)
[euromed] 2019-07-31 12:04:20,337 INFO [Thread-5721] [eu.etaxonomy.cdm.common.monitor.DefaultProgressMonitor] - 99.88129% done (Completed Task: Writing partition 477/478)
[euromed] 2019-07-31 12:04:20,370 INFO [Thread-5721] [eu.etaxonomy.cdm.common.monitor.DefaultProgressMonitor] - 99.88269% done (Completed Task: Writing partition 477/478)
[euromed] 2019-07-31 12:04:20,406 INFO [Thread-5721] [eu.etaxonomy.cdm.common.monitor.DefaultProgressMonitor] - 99.88408% done (Completed Task: Writing partition 477/478)
[euromed] 2019-07-31 12:04:21,001 INFO [Thread-5721] [eu.etaxonomy.cdm.common.monitor.DefaultProgressMonitor] - 99.88548% done (Completed Task: Writing partition 477/478)
[euromed] 2019-07-31 12:04:21,106 INFO [Thread-5721] [eu.etaxonomy.cdm.common.monitor.DefaultProgressMonitor] - 99.88688% done (Completed Task: Writing partition 477/478)
[euromed] 2019-07-31 12:04:21,159 INFO [Thread-5721] [eu.etaxonomy.cdm.common.monitor.DefaultProgressMonitor] - 99.88827% done (Completed Task: Writing partition 477/478)
[euromed] 2019-07-31 12:04:21,214 INFO [Thread-5721] [eu.etaxonomy.cdm.common.monitor.DefaultProgressMonitor] - 99.88967% done (Completed Task: Writing partition 477/478)
[euromed] 2019-07-31 12:04:21,274 INFO [Thread-5721] [eu.etaxonomy.cdm.common.monitor.DefaultProgressMonitor] - 99.89107% done (Completed Task: Writing partition 477/478)
[euromed] 2019-07-31 12:04:21,306 INFO [Thread-5721] [eu.etaxonomy.cdm.common.monitor.DefaultProgressMonitor] - 99.89246% done (Completed Task: Writing partition 477/478)
[euromed] 2019-07-31 12:04:21,346 INFO [Thread-5721] [eu.etaxonomy.cdm.common.monitor.DefaultProgressMonitor] - 99.89386% done (Completed Task: Writing partition 477/478)
[euromed] 2019-07-31 12:04:21,379 INFO [Thread-5721] [eu.etaxonomy.cdm.common.monitor.DefaultProgressMonitor] - 99.89526% done (Completed Task: Writing partition 477/478)
[euromed] 2019-07-31 12:04:21,427 INFO [Thread-5721] [eu.etaxonomy.cdm.common.monitor.DefaultProgressMonitor] - 99.89665% done (Completed Task: Writing partition 477/478)
[euromed] 2019-07-31 12:04:21,467 INFO [Thread-5721] [eu.etaxonomy.cdm.common.monitor.DefaultProgressMonitor] - 99.89805% done (Completed Task: Writing partition 477/478)
[euromed] 2019-07-31 12:04:21,520 INFO [Thread-5721] [eu.etaxonomy.cdm.common.monitor.DefaultProgressMonitor] - 99.89944% done (Completed Task: Writing partition 477/478)
[euromed] 2019-07-31 12:04:21,539 INFO [Thread-5721] [eu.etaxonomy.cdm.common.monitor.DefaultProgressMonitor] - 99.90084% done (Completed Task: Writing partition 477/478)

Reducing the output to report changes only at the first (or second) digit after the decimal point would reduce the amount of reported lines to 1000 (or 10000).

The DefaultProgressMonitors (also others?) should behave differently depending on the loglevel:

• <= DEBUG: log all lines
• >= INFO: log lines only if the number up to the first digit has changed.