From bcfb82d33e431d621317f97d3c0703d9b002a8ee Mon Sep 17 00:00:00 2001
From: typhoonzero <typhoonzero1986@gmail.com>
Date: Mon, 15 Jan 2018 20:55:48 +0800
Subject: [PATCH] dist train support split selectedrows

---
 .../paddle/v2/fluid/distribute_transpiler.py  | 45 +++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/python/paddle/v2/fluid/distribute_transpiler.py b/python/paddle/v2/fluid/distribute_transpiler.py
index d17f9815cc..00fe3e68c9 100644
--- a/python/paddle/v2/fluid/distribute_transpiler.py
+++ b/python/paddle/v2/fluid/distribute_transpiler.py
@@ -59,6 +59,51 @@ def split_dense_variable(var_list,
     return blocks
 
 
+def split_selected_rows(var,
+                        pserver_count,
+                        min_block_size=1024,
+                        max_block_size=1048576):
+    assert ((len(var.shape)) <= 1)
+
+    split_count = pserver_count
+    indices = var.desc.selected_rows().dims()
+    var_width = reduce(lambda x, y: x * y, var.shape[1:])
+    row_count = len(indices)
+    rows_per_block = 1
+    if var_width < min_block_size:
+        rows_per_block = 1
+        split_count = row_count
+    else:
+        rows_per_block = row_count / pserver_count
+        if not rows_per_block % pserver_count:
+            rows_per_block += 1
+        split_count = row_count / rows_per_block
+        if not row_count % rows_per_block:
+            split_count += 1
+    blocks = []
+    for block_id in xrange(split_count):
+        curr_block_rows = min(rows_per_block,
+                              row_count - (block_id * rows_per_block))
+        block = VarBlock(var.name, block_id, curr_block_rows)
+        blocks.append(block)
+    return blocks
+
+
+def split_variable(var_list,
+                   pserver_count,
+                   min_block_size=1024,
+                   max_block_size=1048576):
+    for var in var_list:
+        if var.type == core.VarDesc.VarType.LOD_TENSOR:
+            split_dense_variable(var_list, pserver_count, min_block_size,
+                                 max_block_size)
+        elif var.type == core.VarDesc.VarType.SELECTED_ROWS:
+            split_selected_rows(var_list, pserver_count, min_block_size,
+                                max_block_size)
+        else:
+            raise TypeError("variable must be lodtensor or selected rows")
+
+
 class DistributeTranspiler:
     def transpile(self,
                   optimize_ops,
-- 
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