Deduplicate UserAgent other-info entries - #939
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vuanhphung wants to merge 2 commits into
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UserAgent.withOtherInfo appended to a static list on every call, and asString formatted the whole list under a lock on every request. Callers that register entries per connection, such as the JDBC driver, made request latency and lock contention grow with every connection a JVM had opened. Entries are now stored once in a CopyOnWriteArrayList, so repeated registrations are no-ops and asString reads without locking. The rendered header is unchanged. Co-authored-by: Isaac <no-reply@databricks.com> Signed-off-by: Vu Anh Phung <vu.phung@databricks.com>
ConcurrentHashMap.newKeySet() is the standard concurrent set and adds new entries in constant time, which matters for callers that register many distinct values. Co-authored-by: Isaac <no-reply@databricks.com> Signed-off-by: Vu Anh Phung <vu.phung@databricks.com>
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Closing: the Java SDK source now lives in the monorepo, so this fix is moving there. |
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Summary
Deduplicates
UserAgent.withOtherInfoentries and reads them inasString()without a lock, so registering the same entry repeatedly no longer grows User-Agent state or per-request cost.Why
withOtherInfoappended to a static list on every call, andasString()formatted the whole list under a lock on every request. The Databricks JDBC driver registers its entries on everyDriver.connect(), so in a long-running JVM that opens a connection per query, request latency and lock contention grew with every connection the JVM had opened. In a reproduction against a SQL warehouse (databricks/databricks-jdbc#1714), the list reached 7,280 entries after ~3.7k connections, and 70% of worker CPU samples were inUserAgent.asString. Fixing it in the SDK covers every caller, not just JDBC.What changed
Interface changes
None.
Behavioral changes
Repeated
withOtherInfo/withPartnercalls with the same key and value are no-ops. The rendered User-Agent is unchanged, sinceasString()already removed duplicates.Internal changes
otherInfois aConcurrentHashMap.newKeySet(), andInfoimplementsequals/hashCode. The field is package-private so tests can check its size.How is this tested?
UserAgentTest.testUserAgentWithOtherInfoDeduplicated: 1,000 identical registrations add one entry; the same key with a new value adds another.UserAgentLoadTestnow asserts that 200 concurrent registrations of one entry add it once.Info.equalsis made identity-only.databricks-sdk-javaunit suite passes locally (1,502 tests).This pull request and its description were written by Isaac.