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Page Title

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Hdf rm anchor
AnchorNamesummary
Excerpt

Starts logging metadata cache events if logging was previously enabled.

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Hdf rm anchor
AnchorNameprocedure

Procedure:
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H5F_START_MDC_LOGGING(file_id)

Hdf rm anchor
AnchorNamesignature

Signature:
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<pre><code class="language-c">herr_t H5Fstart_mdc_logging( hid_t file_id )</code></pre>

Hdf rm anchor
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Parameters:
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hid_t file_id   IN: Identifier of an open HDF5 file.

Hdf rm anchor
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Description:
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The metadata cache is a central part of the HDF5 library through which all file metadata reads and writes take place. File metadata is normally invisible to the user and is used by the library for purposes such as locating and indexing data. File metadata should not be confused with user metadata, which consists of attributes created by users and attached to HDF5 objects such as datasets via H5A API calls.

Due to the complexity of the cache, a trace/logging feature has been created that can be used by HDF5 developers for debugging and performance analysis. The functions that control this functionality will normally be of use to a very limited number of developers outside of The HDF Group. The functions have been documented to help users create logs that can be sent with bug reports.

Control of the log functionality is straightforward. Logging is enabled via the H5Pset_mdc_log_options() function, which will modify the file access property list used to open or create a file. This function has a flag that determines whether logging begins at file open or starts in a paused state. Log messages can then be controlled via the H5Fstart/stop_logging() functions. H5Pget_mdc_log_options() can be used to examine a file access property list, and H5Fget_mdc_logging_status() will return the current state of the logging flags.

The log format is described in the Metadata Cache Logging document.

Note

Notes:

Logging can only be started or stopped if metadata cache logging was enabled via H5Pset_mdc_log_options().

When enabled and currently logging, the overhead of the logging feature will almost certainly be significant.

The log file is opened when the HDF5 file is opened or created and not when this function is called for the first time.

This function opens the log file and starts logging metadata cache operations for a particular file. Calling this function when logging has already been enabled will be considered an error.

Hdf rm anchor
AnchorNamereturns

Returns:
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Returns a non-negative value if successful. Otherwise returns a negative value.

Hdf rm anchor
AnchorNameexample

Example:
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Bitbucket Server file
repoSlughdf5
branchIdrefs/heads/1.10/master
projectKeyHDFFV
filepathexamples/h5_subset.c
showLineNumberstrue
lineStart32
progLangcpp
lineEnd42
applicationLink5ac7b370-7412-3c8c-ad20-807a68261336

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Bitbucket Server file
repoSlughdf5
branchIdrefs/heads/1.10/master
projectKeyHDFFV
filepathfortran/examples/compound.f90
showLineNumberstrue
lineStart25
progLangplain
lineEnd35
applicationLink5ac7b370-7412-3c8c-ad20-807a68261336

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togglebox hdf-cxx hdf-togglebox-hidden

Bitbucket Server file
repoSlughdf5
branchIdrefs/heads/1.10/master
projectKeyHDFFV
filepathc++/examples/create.cpp
showLineNumberstrue
lineStart33
progLangcpp
lineEnd43
applicationLink5ac7b370-7412-3c8c-ad20-807a68261336

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Bitbucket Server file
repoSlughdf5
branchIdrefs/heads/1.10/master
projectKeyHDFFV
filepathjava/examples/datasets/H5Ex_D_Chunk.java
showLineNumberstrue
lineStart32
progLangjava
lineEnd42
applicationLink5ac7b370-7412-3c8c-ad20-807a68261336

hdf-rm-anchor
AnchorNamehistory

History:
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ReleaseChange
1.10.0C function introduced with this release.