c8f533cfc3
including the merge of `hdffv/hdf5/develop`, back to the branch that Vailin and I share. Now I need to put this branch on a fork with a less confusing name than vchoi_fork!
151 lines
6.5 KiB
Markdown
151 lines
6.5 KiB
Markdown
VFD SWMR Punch List
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This document lives at [https://bitbucket.hdfgroup.org/users/dyoung/repos/vchoi_fork/browse/doc/VFD_SWMR_Punch_List.md?at=refs%2Fheads%2Ffeature%2Fvfd_swmr](https://bitbucket.hdfgroup.org/users/dyoung/repos/vchoi_fork/browse/doc/VFD_SWMR_Punch_List.md?at=refs%2Fheads%2Ffeature%2Fvfd_swmr)
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An [interactive tutorial](https://www.markdowntutorial.com/) on Markdown
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covers the basics quickly and effectively.
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I know I have used this [Markdown "cheat
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sheet"](https://commonmark.org/help/) before---it provides a nice visual
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guide to the syntax.
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22 November 2019
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1. Design optimizations in index writes. Perhaps write deltas only,
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with a full index every n ticks?
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2. Design work for NFS and object store versions.
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3. Design work for journaling variation.
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4. **Vailin, complete** Add support for opening multiple files in either VFD SWMR writer or
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VFD SWMR writer mode. See addition of the EOT queue in section 3.2.2
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of the RFC, and related changes in sections 3.3 and 3.3.2.
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5. **Vailin, complete**Add the pb\_expansion\_threshold field to the
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H5F\_vfd\_swmr\_config\_t structure, and update
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H5Pset\_vfd\_swmr\_config()and
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H5Pget\_vfd\_swmr\_config()accordingly.
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6. **Vailin, in progress**Implement end tick now API call. See section 3.1.2 of the RFC for
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specifications.
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7. **Vailin, in progress**Implement enable / disable EOT call. See section 3.1.3 of the RFC
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for specifications.
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8. Implement option to flush raw data as part of EOT -- write
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performance test to characterize the performance hit.
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9. **Vailin, complete** Move VFD SWMR specific H5F code to its own file -- say
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H5Fvfd\_swmr.c.
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10. Update the new page buffer to support the pb\_expansion\_threshold,
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and trigger an early end of tick if the threshold is exceeded.
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11. Modify metadata file write call to allow the location of the index
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to float and thus be of arbitrary size.
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12. Add code to remove entries from the index after they have been
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written to the HDF5 file, and have not been modified for at least
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max\_lag ticks.
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13. Tidy short cuts in the initial implementation. These include:
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- **Vailin complete**Odd behavior in the superblock refresh routine (see comments in
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code). Figure out what is going on, and then either bypass the
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issue or fix it as seems appropriate.
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- **Vailin complete**Comment H5F\_vfd\_swmr\_config\_t in H5Fpublic.h properly.
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- Cleanup EOA hack in H5FD\_read().
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- Address file open failures in SWMR tests. These appear to be
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cases in which the writer finishes before the reader opens --
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causing the reader to fail as the metadata file no longer
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exists. If so, handle this more gracefully.
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14. Add support for specifying the VFD that sits under the VFD SWMR
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reader VFD. Probably do this as part of the pluggable VFD design
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that Jake is working on.
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15. Modify the metadata cache so that we don't allocate space for the
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page hash table unless the file is opened in VFD SWMR reader mode.
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16. Implement the logging facility (section 3.14 RFC)
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17. Test code to expose existing page buffer bugs and fix same. Note
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that they seem to appear primarily on Jelly.
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- DLL pre remove sanity check assertion failure
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- vfd\_swmr\_addrem\_writer: H5PB.c:2981:
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H5PB\_\_mark\_entry\_dirty: Assertion
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'(entry\_ptr)-\>delay\_write\_until \> (pb\_ptr)-\>cur\_tick'
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failed.
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18. Flesh out designs for unit, integration and performance tests suites
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as outlined in the RFC. Implement same.
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19. **David, complete** Fix memory leak in sparse-reader test.
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David found that the shadow index was leaked by VFD SWMR readers
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and plugged the leak. Now the sparse reader tests do not use up
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all of the memory on `jelly`. David fixed the bug on his branch
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`vfd_swmr-merge-attempt-2`, which as of 19 Nov 2019 has not been
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merged to `feature/vfd_swmr`.
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20. **David, complete** Test John's patch that repairs the superblock flags
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mismatch that crashes the reader.
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David found that the patch fixed the demo crashes. He applied the
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patch to his branch `vfd_swmr-merge-attempt-2`, which has not yet
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been merged to `feature/vfd_swmr` as of 19 Nov 2019.
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21. Investigate a potential time-of-check, time-of-use race condition
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involving EOA/EOF and the skip\_read variable in some of the H5PB
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routines.
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22. Understand use of H5F\_t on branch feature/vfd\_swmr instead of
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H5C\_t as on develop branch.
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23. *Temporarily* reserve a new superblock flag for VFD SWMR for
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development purposes.
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24. Prior to feature merge, *permanently* reserve a new superblock flag.
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25. Revisit the global heap. The global heap receives data types (a form
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of metadata) and variable-length (VL) data such as strings. It is
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translated to raw data on its way down the HDF5 software stack. If
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the global heap is modified/replaced as currently planned, then VFD
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SWMR does not have to deal with it. However, if the global heap
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overhaul does not take place, then we have more work to do.
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26. **David, complete** Fix the expand/shrink test.
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The test appeared to fail because the dataset extent was enlarged
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before the data was written, so arbitrary data was present.
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If a tick snuck in between the `H5Dset_extent` and
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the `H5Dwrite`, then the reader read the arbitrary data.
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In the `gaussian` test, I have a heuristic that avoids reading
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arbitrary data. Replicating that in the expand/shrink test has
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fixed it. Essentially, the reader trails the writer by a bit.
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Ultimately, we should suspend ticks over the H5Dset_extent/H5Dwrite.
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27. **Vailin, complete** Change the field name "vfd_swmr_writer" to "writer" in
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"struct H5F_vfd_swmr_config_t" and all references to it. See page 11 in the RFC.
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28. **Vailin, complete** Fix bug as stated on page 9 in the RFC section 3.1.1:
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Given that the VFD SWMR configuration FAPL property is set, the writer field must
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be consistent with the flags passed in the H5Fopen() (either H5F_ACC_RDWR for the
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VFD SWMR writer, or H5F_ACC_RDONLY for the VFD SWMR readers).
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29. **Vailin, complete** Fix the FSM bug when setting the FSM threshold to a non-default value.
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The problem was manifested when setting the threshold value in vfd_swmr_generator.c via
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H5Pset_file_space_strategy(fcpl, H5F_FSPACE_STRATEGY_PAGE, FALSE, 1024 * 1024 * 1024) and
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then run the vfd_swmr_addrem_writer.c.
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30. **David, merged, needs more testing** Add a delay to the FSM so that
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freed regions are not reused before max_lag ticks are up.
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