Replace Eventlet with concurrent.futures

- Removed dependencies on Eventlet for asynchronous execution
- Implemented thread pool executor using 'concurrent.futures'
- Updated code to submit tasks and manage futures with
  futures.ThreadPoolExecutor
- Ensured proper waiting for task completion with futures.wait()

Change-Id: Iec6893666c25e03c6d1a6246d41759dc4bff3b24

glance_store/_drivers/s3.py

@@ -15,6 +15,7 @@
 
 """Storage backend for S3 or Storage Servers that follow the S3 Protocol"""
 
+from concurrent import futures
 import io
 import logging
 import math
@@ -32,7 +33,6 @@ except ImportError:
     boto_exceptions = None
     boto_utils = None
 
-import eventlet
 from oslo_config import cfg
 from oslo_utils import encodeutils
 from oslo_utils import units
@@ -726,7 +726,11 @@ class Store(glance_store.driver.Store):
         os_hash_value = utils.get_hasher(hashing_algo, False)
         checksum = utils.get_hasher('md5', False)
         pool_size = self.s3_store_thread_pools
-        pool = eventlet.greenpool.GreenPool(size=pool_size)
+        # Replace eventlet.GreenPool with ThreadPoolExecutor
+        with futures.ThreadPoolExecutor(
+                max_workers=pool_size) as executor:
+            # Create a list to store the futures
+            futures_list = []
             mpu = s3_client.create_multipart_upload(Bucket=bucket, Key=key)
             upload_id = mpu['UploadId']
             LOG.debug("Multipart initiate key=%(key)s, UploadId=%(UploadId)s",
@@ -756,8 +760,11 @@ class Store(glance_store.driver.Store):
                             verifier.update(write_chunk)
                         fp = io.BytesIO(write_chunk)
                         fp.seek(0)
-                    part = UploadPart(mpu, fp, cstart + 1, len(write_chunk))
+                        part = UploadPart(
-                    pool.spawn_n(run_upload, s3_client, bucket, key, part)
+                            mpu, fp, cstart + 1, len(write_chunk))
+                        # Spawn thread to upload part
+                        futures_list.append(executor.submit(
+                            run_upload, s3_client, bucket, key, part))
                         plist.append(part)
                         cstart += 1
                         buffered_chunk = remained_data
@@ -771,26 +778,23 @@ class Store(glance_store.driver.Store):
                             verifier.update(write_chunk)
                         fp = io.BytesIO(write_chunk)
                         fp.seek(0)
-                    part = UploadPart(mpu, fp, cstart + 1, len(write_chunk))
+                        part = UploadPart(
-                    pool.spawn_n(run_upload, s3_client, bucket, key, part)
+                            mpu, fp, cstart + 1, len(write_chunk))
+                        futures_list.append(executor.submit(
+                            run_upload, s3_client, bucket, key, part))
                         plist.append(part)
                     break
 
-        pedict = {}
+        # Wait for all uploads to finish
-        total_size = 0
+        futures.wait(futures_list)
-        pool.waitall()
 
-        for part in plist:
+        # Check success status
-            pedict.update(part.etag)
+        success = all(p.success for p in plist)
-            total_size += part.size
+        total_size = sum(p.size for p in plist)
-
-        success = True
-        for part in plist:
-            if not part.success:
-                success = False
 
         if success:
             # Complete
+            pedict = {p.partnum: p.etag[p.partnum] for p in plist}
             mpu_list = self._get_mpu_list(pedict)
             s3_client.complete_multipart_upload(Bucket=bucket,
                                                 Key=key,