Ghiles OUAREZKI created TIKA-4393:
-------------------------------------
Summary: Thread-safety issue in TikaToXMP.getConverterMap()
Key: TIKA-4393
URL: https://issues.apache.org/jira/browse/TIKA-4393
Project: Tika
Issue Type: Bug
Components: tika-app
Affects Versions: 3.1.0, 2.9.3
Environment: java 8, fedora 3.9, tika 2.9.3
Reporter: Ghiles OUAREZKI
h2. Description:
We execute TikaToXmp conversion in a multithreaded environment where we call
multiple conversion at the same time. According to new parser contribution
guide, there is nothing about thread-safety. During our test, a thread-safety
issue has been found in the getConverterMap() method of the TikaToXMP class in
the tika-xmp module.
We are currently using the 2.9.3 version. We checked in the latest version and
we think the behavior is the same.
h2. Problem:
The method manipulates the static class variable converterMap, but it is not
thread-safe. Since there is no synchronization mechanism, multiple threads can
enter getConverterMap() at the same time and create different instances of
converterMap, leading to potential race conditions.
Current code:
{code:java}
private static Map<MediaType, Class<? extends ITikaToXMPConverter>>
converterMap;
private static Map<MediaType, Class<? extends ITikaToXMPConverter>>
getConverterMap() {
if (converterMap == null) {
converterMap = new HashMap<>();
initialize();
}
return converterMap;
}
{code}
If multiple threads call getConverterMap() simultaneously when converterMap is
still null, they might create multiple instances of converterMap, which can
lead to unexpected behavior.
h2.
Potential solution:
To ensure thread safety, we offer a simple patch : to synchronize
getConverterMap() so that only one thread can initialize converterMap at a
time. The fix consists of adding the *synchronized* keyword to the method:
{code:java}
private static synchronized Map<MediaType, Class<? extends
ITikaToXMPConverter>> getConverterMap() {
if (converterMap == null) {
converterMap = new HashMap<>();
initialize();
}
return converterMap;
}{code}
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
