TomMD commented on a change in pull request #6103:
URL: https://github.com/apache/skywalking/pull/6103#discussion_r550272812
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File path:
apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/plugin/WitnessClassFinder.java
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@@ -36,6 +36,17 @@
* @return true, if the given witnessClass exists, through the given
classLoader.
*/
public boolean exist(String witnessClass, ClassLoader classLoader) {
+ return getResolution(witnessClass, classLoader)
Review comment:
@wu-sheng I don't believe you miss anything, it's merely a difference of
what one considers a race. If you `get` from a variable outside of
synchronized, and that variable is sometimes used in a `synchronized` block
then you receive this read/write race warning.
Your read might race with a write because the lock isn't held. You are
probably unconcerned and can quickly dismiss the warning in this case. The
link you posted suggests you are concern is about races regarding the handling
of the hashmap itself (i.e. the collision and resize issues in the answer) and
it suffices to avoid write/write races.
I believe in practice read/write races are concerning almost exclusively in
multi-variable situations where there are invariants between the variables that
are broken within the writers so the readers must ensure they see a consistent
state, usually with a lock.
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