We just pushed a bugfix update to Synapse 0.5, mainly to fix a memory leak where federated events could get leaked whilst retrying to send them to a remote server which is unavailable. Please upgrade, especially if you've noticed synapse hogging RAM!
Changes in synapse 0.5.4 (2014-12-03) =====================================
- Fix presence bug where some rooms did not display presence updates for remote users.
- Do not log SQL timing log lines when started with "-v"
- Fix potential memory leak.