Hi , I had a question with respect flink memory management / overspill to /tmp.
In the docs (https://ci.apache.org/projects/flink/flink-docs-release-1.6/ops/config.html#configuring-temporary-io-directories) it says: Although Flink aims to process as much data in main memory as possible, it is not uncommon that more data needs to be processed than memory is available. Flink's runtime is designed to write temporary data to disk to handle these situations.... In a flink job that processes a couple streams of 1M events in a windowed co group function with parallelism 8 - we see 8 dirs created in /tmp with 100s of Meg of data, the name of each dir seems aligned to the data for each parallel thread windowing against the co-group operator e.g. bash-4.2$ du -sh * 0 flink-dist-cache-a4a69215-665a-4c3c-8d90-416cbe192f26 352M flink-io-9033517c-ac92-4baa-9e59-79bc80c72a9e 4.0K localState 7.2M rocksdb-lib-03d9460b15e6bf6af4f3d9b0ff7980c3 bash-4.2$ du -sh flink-io-9033517c-ac92-4baa-9e59-79bc80c72a9e/* ... 36M flink-io-9033517c-ac92-4baa-9e59-79bc80c72a9e/job_cf2dca7843dd6b6296aa1a9d15a1d435_op_WindowOperator_014556c228cb5344d41861769d2bbbc1__1_8__uuid_93307150-4f62-4b06-a71e-0230360f7d86 36M flink-io-9033517c-ac92-4baa-9e59-79bc80c72a9e/job_cf2dca7843dd6b6296aa1a9d15a1d435_op_WindowOperator_014556c228cb5344d41861769d2bbbc1__2_8__uuid_7b2f8957-7044-4bb3-869e-28843bd737a1 36M flink-io-9033517c-ac92-4baa-9e59-79bc80c72a9e/job_cf2dca7843dd6b6296aa1a9d15a1d435_op_WindowOperator_014556c228cb5344d41861769d2bbbc1__3_8__uuid_54306a44-7e06-45ae-ba0e-4649887bca7e ... I was wondering can / should this 'over spill' be avoided by increasing the heap of the task manager or another config or should I not worry about it? Is there more information/docs on how this data is used/ cleaned up & what is the cost of this overspill to latency/ checkpointing? Any impact I should be aware of? thanks Anand
Visit our website at http://www.ubs.com This message contains confidential information and is intended only for the individual named. If you are not the named addressee you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately by e-mail if you have received this e-mail by mistake and delete this e-mail from your system. E-mails are not encrypted and cannot be guaranteed to be secure or error-free as information could be intercepted, corrupted, lost, destroyed, arrive late or incomplete, or contain viruses. The sender therefore does not accept liability for any errors or omissions in the contents of this message which arise as a result of e-mail transmission. If verification is required please request a hard-copy version. This message is provided for informational purposes and should not be construed as a solicitation or offer to buy or sell any securities or related financial instruments. UBS Limited is a company limited by shares incorporated in the United Kingdom registered in England and Wales with number 2035362. Registered Office: 5 Broadgate, London EC2M 2QS UBS Limited is authorised by the Prudential Regulation Authority and regulated by the Financial Conduct Authority and the Prudential Regulation Authority. UBS AG is a public company incorporated with limited liability in Switzerland domiciled in the Canton of Basel-City and the Canton of Zurich respectively registered at the Commercial Registry offices in those Cantons with new Identification No: CHE-101.329.561 as from 18 December 2013 (and prior to 18 December 2013 with Identification No: CH-270.3.004.646-4) and having respective head offices at Aeschenvorstadt 1, 4051 Basel and Bahnhofstrasse 45, 8001 Zurich, Switzerland and is authorised and regulated by the Financial Market Supervisory Authority in Switzerland. Registered in the United Kingdom as a foreign company with No: FC021146 and having a UK Establishment registered at Companies House, Cardiff, with No: BR 004507. The principal office of UK Establishment: 5 Broadgate, London EC2M 2QS. In the United Kingdom, UBS AG is authorised by the Prudential Regulation Authority and subject to regulation by the Financial Conduct Authority and limited regulation by the Prudential Regulation Authority. Details about the extent of our regulation by the Prudential Regulation Authority are available from us on request. UBS Business Solutions AG is a public company incorporated with limited liability in Switzerland domiciled in the Canton of Zurich registered at the Commercial Registry office with Identification No: CHE-262.289.477 and having its head office at Bahnhofstrasse 45, 8001 Zurich, Switzerland. Registered in the United Kingdom as a foreign company with No: FC034139 and having a UK Establishment registered at Companies House, Cardiff, with No: BR019277. The principal office of UK Establishment: 5 Broadgate London EC2M 2QS. UBS reserves the right to retain all messages. Messages are protected and accessed only in legally justified cases.