Prakash Udupa created TRINIDAD-2484:
---------------------------------------
Summary: Threadsafety issue in SkinStyleProvider leading to
missing styles and distorted ui
Key: TRINIDAD-2484
URL: https://issues.apache.org/jira/browse/TRINIDAD-2484
Project: MyFaces Trinidad
Issue Type: Bug
Components: Skinning
Affects Versions: 2.1.0-core
Reporter: Prakash Udupa
We have seen that soon after server start, when there are almost concurrent
requests from IE, in random occurrences, there will be only one link encoded in
the HTML, while there are two css files generated. Consequently, styles for
some components in the page could go missing, ending up in distorted UI in
certain sections of the rendered page.
We suspect the cause to be a thread safety issue in SkinStyleProvider
implementation where we construct style providers and save it in map keyed by
skin and the directory path of the css. The issue is in _getProviders()
implementation, where the variable _sSharedProviders is not accessed in
threadsafe manner. This leads to possibility of the providers map being
overwritten. This further leads to constructing two SkinStyleProviders for the
same skin. While one request could use one provider (P1) that is in process of
writing out one css file with the second one pending, there could be other
request that ends up using a different provider (P2) that would see a single
file written, and end up adding single URI in its Entry map. All requests later
could end up using P2 and sufferring from only one link being rendered, while
there are two stylesheets actually generated.
Proposed fix is to eliminate "_sSharedProviders", and instead use the
application scoped concurrent map hanging off of request scope to store the
provider map. We can then leverage on the putIfAbsent in there to ensure there
is only one copy of providers map for an application.
--
This message was sent by Atlassian JIRA
(v6.2#6252)
