Author: schor
Date: Fri Aug 19 21:50:23 2016
New Revision: 1756969
URL: http://svn.apache.org/viewvc?rev=1756969&view=rev
Log:
no Jira - add secton on limited multi-threaded access to read-only CASs to the
reference doc.
Modified:
uima/uimaj/trunk/uima-docbook-references/src/docbook/ref.cas.xml
Modified: uima/uimaj/trunk/uima-docbook-references/src/docbook/ref.cas.xml
URL:
http://svn.apache.org/viewvc/uima/uimaj/trunk/uima-docbook-references/src/docbook/ref.cas.xml?rev=1756969&r1=1756968&r2=1756969&view=diff
==============================================================================
--- uima/uimaj/trunk/uima-docbook-references/src/docbook/ref.cas.xml (original)
+++ uima/uimaj/trunk/uima-docbook-references/src/docbook/ref.cas.xml Fri Aug 19
21:50:23 2016
@@ -1107,4 +1107,25 @@ FSIterator it = cas.createFilteredIterat
with the same name can be merged only if their features can be merged.
</para>
</section>
+
+ <section id="ugr.ref.cas.limitedmultipleaccess">
+ <title>Limited multi-thread access to read-only CASs</title>
+
+ <para>Some applications may find it useful to scale up pipelines and run
these in parallel.</para>
+ <para>
+ Generally, CASs are not threadsafe, and only one thread at a time may
operate on it. In many
+ scenarios, a CAS may be initialized and then filled with Feature
Structures, and after some point,
+ no more updates to that particular CAS will be done.</para>
+
+ <para>
+ If a CAS is no longer going to be changed, it is possible to
+ access it on multiple threads in a read-only mode, simultaneously, with
some limitations. Limitations
+ arise because some UIMA Framework activities may update internal CAS data
structures.</para>
+
+ <para>Operational data is updated while running a pipeline when a PEAR is
entered or exited,
+ because PEARs establish new class loaders and can potentially switch the
JCas classes being used.
+ Because of this, you cannot have multiple pipelines accessing a CAS in
read-only mode if one or more of those
+ pipelines contains a PEAR.
+ </para>
+ </section>
</chapter>
\ No newline at end of file
