Update CHANGES.md to document a memory growth issue. (#39407)

* Update CHANGES.md

* Fix AI review comments

Author: tvalentyn

CHANGES.md

@@ -84,7 +84,7 @@
 
 * Fixed unbounded checkpoint state growth for splittable DoFns that self-checkpoint on the portable Flink runner (Java) ([#27648](https://github.com/apache/beam/issues/27648)).
 * Improved Java pipeline performance by avoiding repeated `DoFn` type descriptor resolution when creating cached invokers ([#39309](https://github.com/apache/beam/issues/39309)).
-* Fixed X (Java/Python) ([#X](https://github.com/apache/beam/issues/X)).
+* (Python) Fixed a memory leak in Python SDK caused by storing exceptions with potentially large stack frames in a cache ([#39406](https://github.com/apache/beam/issues/39406)).
 
 ## Security Fixes
 
@@ -138,6 +138,7 @@
 ## Known Issues
 
 * (Java) Projects using the Flink runner with Flink 2.1 or later alongside libraries requiring `org.lz4:lz4-java` (e.g., Kafka clients) may encounter a Gradle capability conflict, because Flink 2.1+ ships `at.yawk.lz4:lz4-java` which declares the same capability. To resolve, add a `capabilitiesResolution` rule to your `build.gradle` that selects `at.yawk.lz4:lz4-java` ([#38947](https://github.com/apache/beam/issues/38947)).
+* (Python) Long-running Python pipelines might experience memory growth and periodic OOMs ([#39406](https://github.com/apache/beam/issues/39406)).
 
 # [2.74.0] - 2026-06-02
 
@@ -179,6 +180,10 @@
 * Fixed BigQueryEnrichmentHandler batch mode dropping earlier requests when multiple requests share the same enrichment key (Python) ([#38035](https://github.com/apache/beam/issues/38035)).
 * Added `max_batch_duration_secs` passthrough support in Python Enrichment BigQuery and CloudSQL handlers so batching duration can be forwarded to `BatchElements` ([#38243](https://github.com/apache/beam/issues/38243)).
 
+## Known Issues
+
+* (Python) Long-running Python pipelines might experience memory growth and periodic OOMs ([#39406](https://github.com/apache/beam/issues/39406)).
+
 # [2.73.0] - 2026-04-29
 
 ## Highlights
@@ -215,6 +220,10 @@
 * Fixed [CVE-2023-46604](https://www.cve.org/CVERecord?id=CVE-2023-46604) (CVSS 10.0) and [CVE-2022-41678](https://www.cve.org/CVERecord?id=CVE-2022-41678) by upgrading ActiveMQ from 5.14.5 to 5.19.2 (Java) ([#37943](https://github.com/apache/beam/issues/37943)).
 * Fixed [CVE-2024-1597](https://www.cve.org/CVERecord?id=CVE-2024-1597), [CVE-2022-31197](https://www.cve.org/CVERecord?id=CVE-2022-31197), and [CVE-2022-21724](https://www.cve.org/CVERecord?id=CVE-2022-21724) by upgrading PostgreSQL JDBC Driver from 42.2.16 to 42.6.2 (Java) ([#37942](https://github.com/apache/beam/issues/37942)).
 
+## Known Issues
+
+* (Python) Long-running Python pipelines might experience memory growth and periodic OOMs ([#39406](https://github.com/apache/beam/issues/39406)).
+
 # [2.72.0] - 2026-03-30
 
 ## Highlights
@@ -248,6 +257,10 @@
 
 * Fixed [CVE-2024-28397](https://www.cve.org/CVERecord?id=CVE-2024-28397) by switching from js2py to pythonmonkey (Yaml) ([#37560](https://github.com/apache/beam/issues/37560)).
 
+## Known Issues
+
+* (Python) Long-running Python pipelines might experience memory growth and periodic OOMs ([#39406](https://github.com/apache/beam/issues/39406)).
+
 # [2.71.0] - 2026-01-22
 
 ## I/Os
@@ -269,6 +282,7 @@
 
 ## Known Issues
 
+* (Python) Long-running Python pipelines might experience memory growth and periodic OOMs ([#39406](https://github.com/apache/beam/issues/39406)).
 
 # [2.70.0] - 2025-12-16
 
@@ -291,6 +305,10 @@ Now Beam has full support for Milvus integration including Milvus enrichment and
 
 * (Python) Python 3.9 reached EOL in October 2025 and support for the language version has been removed. ([#36665](https://github.com/apache/beam/issues/36665)).
 
+## Known Issues
+
+* (Python) Long-running Python pipelines might experience memory growth and periodic OOMs ([#39406](https://github.com/apache/beam/issues/39406)).
+
 # [2.69.0] - 2025-10-28
 
 ## Highlights
@@ -350,6 +368,10 @@ Now Beam has full support for Milvus integration including Milvus enrichment and
   ([#36141](https://github.com/apache/beam/issues/36141)).
 * Fixed Spanner Change Stream reading stuck issue due to watermark of partition moving backwards ([#36470](https://github.com/apache/beam/issues/36470)).
 
+## Known Issues
+
+* (Python) Long-running Python pipelines might experience memory growth and periodic OOMs ([#39406](https://github.com/apache/beam/issues/39406)).
+
 # [2.68.0] - 2025-09-22
 
 ## Highlights
@@ -404,6 +426,7 @@ Now Beam has full support for Milvus integration including Milvus enrichment and
 ## Known Issues
 
 * ([#36470](https://github.com/apache/beam/issues/36470)). Spanner Change Stream reading stuck issue due to watermark of partition moving backwards. This issue exists in 2.67.0 and 2.68.0. To mitigate the issue, either use old version 2.66.0 or go to 2.69.0.
+* (Python) Long-running Python pipelines might experience memory growth and periodic OOMs ([#39406](https://github.com/apache/beam/issues/39406)).
 
 # [2.67.0] - 2025-08-12
 
@@ -452,6 +475,7 @@ Now Beam has full support for Milvus integration including Milvus enrichment and
 
 * ([#35666](https://github.com/apache/beam/issues/35666)). YAML Flatten incorrectly drops fields when input PCollections' schema are different. This issue exists for all versions since 2.52.0.
 * ([#36470](https://github.com/apache/beam/issues/36470)). Spanner Change Stream reading stuck issue due to watermark of partition moving backwards. This issue exists in 2.67.0 and 2.68.0. To mitigate the issue, either use old version 2.66.0 or go to 2.69.0.
+* (Python) Long-running Python pipelines might experience memory growth and periodic OOMs ([#39406](https://github.com/apache/beam/issues/39406)).
 
 # [2.66.0] - 2025-07-01