Complex models do not provide many opportunities to save the status of the task to disk. Some projects would just grind to a halt and make the PC less responsive. It is the objective of World Community Grid to ensure that this does not happen and make the process strictly 'in the background and unobtrusive'. For that reason checkpoints are used to secure the data already computed. These checkpoints also are a good moment to close the BOINC client without it resulting in substantial progress loss on restart. The timing of checkpoints are not always easily to determine, but sometimes the graphics provide a visual indication.
|Science Project||Checkpoint feature description||Screenshot|
|When the Best Energy C graph green line has reached the end and returns to the beginning, whilst rescaling the graph and adding a red line indicating the path of the previous attempt. The times between checkpoints is variable depending on speed of device, complexity of the docking run which due it's non-deterministic nature quite variable.|
|Occurs after each structure attempt. Looking at the left side 3 line graphs, one can see how far along one is. When they reach the end of the X axis and restart at the left, the structure investigation is complete and a checkpoint occurs. Due the non-deterministic nature of the computations times between checkpoints can be from fair to reasonable far apart.|
|The checkpoints are in incremental steps of 0.2 to 0.25% progress, about once per minute, thus the relative loss on shutdown and resume is minimal.|
|This project checkpoints after each filter round. Unusual the first takes about 5 minutes to complete and write a checkpoint save. Thereafter the timespan increases progressively to the end of the work unit where it can take 30 - 60 minutes, sometimes more on slower devices.|
|This project has a fixed run time and checkpoint space lasting from under 1 minute to several minutes.|
|This project has 3 types of tasks identified by an A, B or C in the result name. Checkpoints occur approximately every 3 minutes thus stop and restart loss of time is minimal|
|As with all AutoDock projects, checkpoint frequency can vary. A checkpoint is saved after every docking attempt; this can vary from more than 20 attempts to (in rare cases) only a few. A typical checkpoint interval is 10 minutes.|
|Checkpoints are saved at end of each 'position' and can take from just seconds to several hours depending on the speed of the device and the complexity of the individual position. The next position is accompanied with a colour change. These changes are pure random, thus could on outside chance assume same colour even if checkpoint was reached.|
Some of these checkpoints usually translate to some or considerable flickering of the hard drive light for a number of seconds, but only if the files to save are larger. The graphical screens for this agent has less detailed elements or depending on operating system are not available. To see them, go to the Tasks tab of the advanced view (version >= 5.8), select the task in progress and click the 'Show Graphics' button in the left margin. If the button is grayed, no graphics are available.
Accurate time intervals cannot be given between checkpoints as they are very dependent on the speed of the computer and how much idle time is available to perform the science projects.
When running on BOINC and interested to see an actual record of check-pointing shown in the Message Tab, you need to create or edit a file called cc_config.xml  and turn on the logging with <task_debug>1</task_debug>. Restart BOINC or from 5.8.11 and up, use the 'Advanced' menu > 'Read Config File' to activate the additional message recording. Deactivation can be done by replacing the 1 by 0 and repeat the restart/read action. Set your BOINC throttle at 100% otherwise you will get a ton of output (other utilities can emulate the throttle outside of BOINC!).
From BOINC version 5.8.16 logging of all checkpoints can be activated with the <checkpoint_debug>1</checkpoint_debug> log flag entry in the cc_config.xml file. All parameters in this file can be changed with a text-editor and effectuated immediately by using the 'Advanced' > 'Read Config File' menu option.
2-3-2007 0:29:55|WCG|[checkpoint_debug] result faah1368_d116n672_x2BPW_00_2 checkpointed 2-3-2007 0:34:51|WCG|[checkpoint_debug] result faah1368_d116n693_x2BPW_01_1 checkpointed 2-3-2007 0:46:48|WCG|[checkpoint_debug] result faah1368_d116n693_x2BPW_01_1 checkpointed
- Hibernation, a good way to not incur progress loss on resume, is covered in a separate post in this 'Start Here ' forum.
- When electing to not crunch during computer use aka run in a idle/resume setup with the "while computer is in use" option deselected and "Leave application in memory when suspended" (LIM), the sciences will unload from memory each time the device receives mouse/keyboard input. This results in the application to restart at the last checkpoint after the idle/resume time has passed. If enough RAM is available, say 1gb base plus 256mb for each processor core in the computer, it is better to switch the LIM option on. Generally for most people BOINC processing while doing work at the computer is unnoticeable. BOINC runs at lowest priority giving way to all user input and other application which normally run at normal priority. See related topic for details.
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