async & sync programing

src/intermediate/async_code.py

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+# # Normally in Python, code runs synchronously → one line after another
+# # Asynchronous programming lets your program do other work while waiting for slow tasks.
+# # Python provides this via the asyncio library with:
+# # async def → defines an asynchronous function(coroutine)
+# # await → pauses execution until an async task finishes
+# # asyncio.run() → starts the event loop
+
+
+import time
+import asyncio
+
+
+# Example 1: Normal(Synchronous)
+
+def download_file(file_name):
+    print(f"Downloading file {file_name}")
+    time.sleep(3)
+    print(f"{file_name} downloaded")
+
+
+def run_example_1():
+    download_file("file1.txt")
+    download_file("file2.txt")
+
+
+# Example 2 Asynchronous with asyncio
+
+
+async def my_task():
+    print("Running async task")
+
+# we have to run the async program through the asyncio.run method it’s the entry point for async programs
+# it's creates an event loop, runs your async function, and closes the loop
+asyncio.run(my_task())
+
+
+async def async_download_file(file_name):
+    print(f"Downloading {file_name}...")
+    await asyncio.sleep(2)  # non-blocking wait
+    print(f"{file_name} downloaded")
+
+
+async def call_async_fileDownload():
+    # With asyncio.gather(concurrent)
+    await asyncio.gather(
+        async_download_file("file_async1.txt"),
+        async_download_file("file_async2.txt")
+    )
+
+
+async def call_async_fileDownload_sequential():
+    # sequential
+    await async_download_file("file_async1.txt"),
+    await async_download_file("file_async2.txt")
+
+
+async def task(name, delay):
+    print(f"Starting {name}")
+    await asyncio.sleep(delay)
+    print(f"Finished {name}")
+    return name
+
+
+async def run_at_once():
+    # Run both tasks at once
+    results = await asyncio.gather(
+        task("A", 1),
+        task("B", 5)
+    )
+    print(results)  # gather function gives list of results
+    print(results[0])
+
+
+if __name__ == "__main__":
+
+    # This will take 4 seconds (because tasks run one after another)
+    run_example_1()
+
+    # This will finish in ~2 seconds, because both tasks run concurrently.
+    asyncio.run(call_async_fileDownload())
+
+    asyncio.run(call_async_fileDownload_sequential())
+    asyncio.run(run_at_once())