From 88996eddcbbe7582547a66db67f23b6478504efd Mon Sep 17 00:00:00 2001
From: ciaranbor <ciaranborourke-dev@proton.me>
Date: Wed, 3 Dec 2025 19:05:56 +0000
Subject: [PATCH] Further refactor

---
 .../worker/engines/mflux/generator/flux1.py   |  3 +-
 src/exo/worker/engines/mflux/shard_mflux.py   | 46 ++++++++++++-------
 src/exo/worker/engines/mflux/utils_mflux.py   | 25 ++++------
 3 files changed, 38 insertions(+), 36 deletions(-)

diff --git a/src/exo/worker/engines/mflux/generator/flux1.py b/src/exo/worker/engines/mflux/generator/flux1.py
index 22cf2623..aec26874 100644
--- a/src/exo/worker/engines/mflux/generator/flux1.py
+++ b/src/exo/worker/engines/mflux/generator/flux1.py
@@ -1,4 +1,5 @@
 from typing import Literal
+
 import mlx.core as mx
 from mflux.callbacks.callbacks import Callbacks
 from mflux.config.config import Config
@@ -13,8 +14,6 @@ from mflux.utils.image_util import ImageUtil
 from PIL import Image
 from tqdm import tqdm
 
-from exo.shared.types.api import ImageGenerationTaskParams
-
 
 def _generate_image(model: Flux1, settings: Config, prompt: str, seed: int):
     # 0. Create a new runtime config based on the model type and input parameters
diff --git a/src/exo/worker/engines/mflux/shard_mflux.py b/src/exo/worker/engines/mflux/shard_mflux.py
index ad4ae744..3855c5ba 100644
--- a/src/exo/worker/engines/mflux/shard_mflux.py
+++ b/src/exo/worker/engines/mflux/shard_mflux.py
@@ -13,6 +13,7 @@ from exo.shared.types.worker.shards import (
     ShardMetadata,
     TensorShardMetadata,
 )
+from exo.worker.engines.mlx.utils_mlx import mx_barrier
 
 
 class _JointBlock(Protocol):
@@ -278,23 +279,9 @@ class FluxSingleSyncBlock(CustomMlxSingleBlock):
         return hidden_states
 
 
-def shard_flux_transformer(
-    model: Flux1,
-    group: mx.distributed.Group,
-    shard_metadata: ShardMetadata,
-) -> Flux1:
-    if isinstance(shard_metadata, TensorShardMetadata):
-        raise NotImplementedError(
-            "Tensor parallelism is not yet supported for Flux models. "
-            "Use pipeline parallelism instead."
-        )
-
-    if not isinstance(shard_metadata, PipelineShardMetadata):
-        raise ValueError(
-            f"Unsupported shard metadata type: {type(shard_metadata)}. "
-            "Expected PipelineShardMetadata."
-        )
-
+def pipeline_transformer(
+    model: Flux1, group: mx.distributed.Group, shard_metadata: ShardMetadata
+):
     transformer: Transformer = model.transformer
 
     # Total = joint blocks + single blocks
@@ -385,3 +372,28 @@ def shard_flux_transformer(
     transformer.single_transformer_blocks = assigned_single_blocks
 
     return model
+
+
+def shard_flux_transformer(
+    model: Flux1,
+    group: mx.distributed.Group,
+    shard_metadata: ShardMetadata,
+) -> Flux1:
+    match shard_metadata:
+        case TensorShardMetadata():
+            raise NotImplementedError(
+                "Tensor parallelism is not yet supported for Flux models. "
+                "Use pipeline parallelism instead."
+            )
+        case PipelineShardMetadata():
+            model = pipeline_transformer(model, group, shard_metadata)
+
+    mx.eval(model.parameters())
+
+    # TODO: Do we need this?
+    mx.eval(model)
+
+    # Synchronize processes before generation to avoid timeout
+    mx_barrier(group)
+
+    return model
diff --git a/src/exo/worker/engines/mflux/utils_mflux.py b/src/exo/worker/engines/mflux/utils_mflux.py
index 7b8554a8..89aea3d3 100644
--- a/src/exo/worker/engines/mflux/utils_mflux.py
+++ b/src/exo/worker/engines/mflux/utils_mflux.py
@@ -12,29 +12,20 @@ def initialize_mflux(bound_instance: BoundInstance) -> Flux1:
     model_id = bound_instance.bound_shard.model_meta.model_id
     model_path = build_model_path(model_id)
 
+    # TODO: generalise
+    model = Flux1(
+        model_config=ModelConfig.from_name(model_name=model_id, base_model=None),
+        local_path=str(model_path),
+        # quantize=8,
+    )
+
     is_distributed = len(bound_instance.instance.shard_assignments.node_to_runner) > 1
 
-    if not is_distributed:
-        # Single-node: load full model normally
-        logger.info(f"Single device used for {bound_instance.instance}")
-        model = Flux1(
-            model_config=ModelConfig.from_name(model_name=model_id, base_model=None),
-            local_path=str(model_path),
-            # quantize=8,
-        )
-    else:
+    if is_distributed:
         # Multi-node: initialize distributed and shard transformer
         logger.info("Starting distributed init for Flux")
         group = mlx_distributed_init(bound_instance)
 
-        logger.info("Loading Flux model for distributed inference")
-        model = Flux1(
-            model_config=ModelConfig.from_name(model_name=model_id, base_model=None),
-            local_path=str(model_path),
-            # quantize=8,
-        )
-
-        logger.info("Applying pipeline parallelism to Flux transformer")
         model = shard_flux_transformer(
             model=model,
             group=group,