[GitHub] [incubator-mxnet] eric-haibin-lin commented on a change in pull request #15124: [MXNET-1294] Priority-based parameter propagation for improved data parallel training throughput

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eric-haibin-lin commented on a change in pull request #15124: [MXNET-1294] Priority-based parameter propagation for improved data parallel training throughput
URL: https://github.com/apache/incubator-mxnet/pull/15124#discussion_r291451322
 
 

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 File path: src/kvstore/kvstore_dist.h
 ##########
 @@ -412,17 +439,38 @@ class KVStoreDist : public KVStoreLocal {
 
   void PushDefault(int key, const NDArray &send_buf, const PSKV& pskv, int priority) {
     auto push_to_servers =
-        [this, key, pskv, send_buf](RunContext rctx, Engine::CallbackOnComplete cb) {
+        [this, key, pskv, send_buf, priority](RunContext rctx, Engine::CallbackOnComplete cb) {
           const int dtype = send_buf.dtype();
           // convert to ps keys
           const size_t size = send_buf.shape().Size() * mshadow::mshadow_sizeof(dtype);
           char* data = static_cast<char *>(send_buf.data().dptr_);
           // do push. false means no delete
           ps::SArray<char> vals(data, size, false);
           int cmd = GetCommandType(RequestType::kDefaultPushPull, dtype);
-          CHECK_NOTNULL(ps_worker_)->ZPush(
-              pskv.keys, vals, pskv.lens,
-              cmd, [cb]() { cb(); });
+
+          auto *counter = new std::atomic<int>(pskv.keys.size());
+          int len = 0;
+          for (size_t i = 0; i < pskv.keys.size(); i++) {
+            auto ks = new ps::SArray<ps::Key>(std::move(pskv.keys.segment(i, i+1)));
+            auto vs = new ps::SArray<char>(std::move(vals.segment(len, len+pskv.lens[i])));
+            auto ls = new ps::SArray<int>(std::move(pskv.lens.segment(i, i+1)));
+            CHECK_NOTNULL(ps_worker_)->ZPush(*ks, *vs, *ls,
+                    static_cast<int>(RequestType::kDefaultPushPull),
 
 Review comment:
   Hmmm. We cannot assume users call kv.pull after kv.push is called. It is legal for a user to call `kv.push` multiple times before a `kv.pull` is called. 

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