[core] Add an example for RAY_DEDUP_LOGS_SKIP_REGEX (#47913)

Signed-off-by: kaihsun <kaihsun@anyscale.com>

.vale/styles/config/vocabularies/General/accept.txt

@@ -17,3 +17,5 @@ GKE
 namespace
 ARM
 breakpoint
+deduplicate[s]
+deduplication

doc/source/ray-observability/user-guides/configure-logging.md

@@ -62,7 +62,7 @@ System logs may include information about your applications. For example, ``runt
   This is the log file of the agent containing logs of create or delete requests and cache hits and misses.
   For the logs of the actual installations (for example, ``pip install`` logs), see the ``runtime_env_setup-[job_id].log`` file (see below).
 - ``runtime_env_setup-ray_client_server_[port].log``: Logs from installing {ref}`Runtime Environments <runtime-environments>` for a job when connecting with {ref}`Ray Client <ray-client-ref>`.
-- ``runtime_env_setup-[job_id].log``: Logs from installing {ref}`Runtime Environments <runtime-environments>` for a Task, Actor or Job.  This file is only present if a Runtime Environment is installed.
+- ``runtime_env_setup-[job_id].log``: Logs from installing {ref}`runtime environments <runtime-environments>` for a Task, Actor, or Job. This file is only present if you install a runtime environment.
 
 
 (log-redirection-to-driver)=
@@ -136,13 +136,58 @@ The output is as follows:
 (task pid=534174) Hello there, I am a task 0.17536720316370757 [repeated 99x across cluster] (Ray deduplicates logs by default. Set RAY_DEDUP_LOGS=0 to disable log deduplication)
 ```
 
-This feature is especially useful when importing libraries such as `tensorflow` or `numpy`, which may emit many verbose warning messages when imported. Configure this feature as follows:
-
-1. Set ``RAY_DEDUP_LOGS=0`` to disable this feature entirely.
-2. Set ``RAY_DEDUP_LOGS_AGG_WINDOW_S=<int>`` to change the agggregation window.
-3. Set ``RAY_DEDUP_LOGS_ALLOW_REGEX=<string>`` to specify log messages to never deduplicate.
-4. Set ``RAY_DEDUP_LOGS_SKIP_REGEX=<string>`` to specify log messages to skip printing.
-
+This feature is useful when importing libraries such as `tensorflow` or `numpy`, which may emit many verbose warning messages when you import them. 
+
+Configure the following environment variables on the driver process **before importing Ray** to customize log deduplication:
+
+* Set ``RAY_DEDUP_LOGS=0`` to turn off this feature entirely.
+* Set ``RAY_DEDUP_LOGS_AGG_WINDOW_S=<int>`` to change the aggregation window.
+* Set ``RAY_DEDUP_LOGS_ALLOW_REGEX=<string>`` to specify log messages to never deduplicate.
+    * Example:
+        ```python
+        import os
+        os.environ["RAY_DEDUP_LOGS_ALLOW_REGEX"] = "ABC"
+
+        import ray
+
+        @ray.remote
+        def f():
+            print("ABC")
+            print("DEF")
+
+        ray.init()
+        ray.get([f.remote() for _ in range(5)])
+
+        # 2024-10-10 17:54:19,095 INFO worker.py:1614 -- Connecting to existing Ray cluster at address: 172.31.13.10:6379...
+        # 2024-10-10 17:54:19,102 INFO worker.py:1790 -- Connected to Ray cluster. View the dashboard at 127.0.0.1:8265
+        # (f pid=1574323) ABC
+        # (f pid=1574323) DEF
+        # (f pid=1574321) ABC
+        # (f pid=1574318) ABC
+        # (f pid=1574320) ABC
+        # (f pid=1574322) ABC
+        # (f pid=1574322) DEF [repeated 4x across cluster] (Ray deduplicates logs by default. Set RAY_DEDUP_LOGS=0 to disable log deduplication, or see https://docs.ray.io/en/master/ray-observability/user-guides/configure-logging.html#log-deduplication for more options.)
+        ```
+* Set ``RAY_DEDUP_LOGS_SKIP_REGEX=<string>`` to specify log messages to skip printing.
+    * Example:
+        ```python
+        import os
+        os.environ["RAY_DEDUP_LOGS_SKIP_REGEX"] = "ABC"
+
+        import ray
+
+        @ray.remote
+        def f():
+            print("ABC")
+            print("DEF")
+
+        ray.init()
+        ray.get([f.remote() for _ in range(5)])
+        # 2024-10-10 17:55:05,308 INFO worker.py:1614 -- Connecting to existing Ray cluster at address: 172.31.13.10:6379...
+        # 2024-10-10 17:55:05,314 INFO worker.py:1790 -- Connected to Ray cluster. View the dashboard at 127.0.0.1:8265
+        # (f pid=1574317) DEF
+        # (f pid=1575229) DEF [repeated 4x across cluster] (Ray deduplicates logs by default. Set RAY_DEDUP_LOGS=0 to disable log deduplication, or see https://docs.ray.io/en/master/ray-observability/user-guides/configure-logging.html#log-deduplication for more options.)
+        ```
 
 
 ## Distributed progress bars (tqdm)