YQ-727 S3 coro read with backpressure.

ref:a4e27ef29e20da0131d9e6638d8ae2dc6832ef6b

4 files changed, 193 insertions, 97 deletions

diff --git a/ydb/library/yql/providers/common/http_gateway/yql_http_gateway.cpp b/ydb/library/yql/providers/common/http_gateway/yql_http_gateway.cpp
index c9b16436abe..8895c05587f 100644
--- a/ydb/library/yql/providers/common/http_gateway/yql_http_gateway.cpp
+++ b/ydb/library/yql/providers/common/http_gateway/yql_http_gateway.cpp
@@ -16,10 +16,9 @@ namespace {
 class TEasyCurl {
 public:
     using TPtr = std::shared_ptr<TEasyCurl>;
-    using TWeakPtr = std::weak_ptr<TEasyCurl>;
 
-    TEasyCurl(const NMonitoring::TDynamicCounters::TCounterPtr&  counter, const NMonitoring::TDynamicCounters::TCounterPtr& downloadedBytes, TString url, IHTTPGateway::THeaders headers, std::size_t offset, std::size_t expectedSize, bool withData)
-        : Offset(offset), ExpectedSize(expectedSize), Handle(curl_easy_init()), Counter(counter), DownloadedBytes(downloadedBytes)
+    TEasyCurl(const NMonitoring::TDynamicCounters::TCounterPtr&  counter, const NMonitoring::TDynamicCounters::TCounterPtr& downloadedBytes, TString url, IHTTPGateway::THeaders headers, size_t offset, bool withData)
+        : Offset(offset), Handle(curl_easy_init()), Counter(counter), DownloadedBytes(downloadedBytes)
     {
         curl_easy_setopt(Handle, CURLOPT_URL, url.c_str());
         curl_easy_setopt(Handle, CURLOPT_POST, withData ?  1L : 0L);
@@ -53,22 +52,19 @@ public:
         }
     }
 
-    std::size_t GetExpectedSize() const {
-        return ExpectedSize;
-    }
-
     CURL* GetHandle() const {
         return Handle;
     }
 
-    // return true if callback successfully added to this work
-    virtual bool AddCallback(IHTTPGateway::TOnResult callback) = 0;
     virtual void Fail(const TIssue& error) = 0;
     virtual void Done(CURLcode result) = 0;
 
     virtual size_t Write(void* contents, size_t size, size_t nmemb) = 0;
     virtual size_t Read(char *buffer, size_t size, size_t nmemb) = 0;
-
+protected:
+    void SkipTo(size_t offset) const {
+        curl_easy_setopt(Handle, CURLOPT_RANGE,  (ToString(Offset + offset) += '-').c_str());
+    }
 private:
     static size_t
     WriteMemoryCallback(void* contents, size_t size, size_t nmemb, void* userp) {
@@ -82,8 +78,7 @@ private:
         return static_cast<TEasyCurl*>(userp)->Read(buffer, size, nmemb);
     };
 
-    const std::size_t Offset;
-    const std::size_t ExpectedSize;
+    const size_t Offset;
     CURL *const Handle;
     curl_slist* Headers = nullptr;
     const NMonitoring::TDynamicCounters::TCounterPtr Counter;
@@ -92,25 +87,33 @@ private:
 
 class TEasyCurlBuffer : public TEasyCurl {
 public:
-    TEasyCurlBuffer(const NMonitoring::TDynamicCounters::TCounterPtr& counter, const NMonitoring::TDynamicCounters::TCounterPtr& downloadedBytes, TString url, TString data, IHTTPGateway::THeaders headers, std::size_t offset, std::size_t expectedSize, IHTTPGateway::TOnResult callback)
-        : TEasyCurl(counter, downloadedBytes, url, headers, offset, expectedSize, !data.empty()), Data(std::move(data)), Input(Data), Output(Buffer)
+    using TPtr = std::shared_ptr<TEasyCurlBuffer>;
+    using TWeakPtr = std::weak_ptr<TEasyCurlBuffer>;
+
+    TEasyCurlBuffer(const NMonitoring::TDynamicCounters::TCounterPtr&  counter, const NMonitoring::TDynamicCounters::TCounterPtr& downloadedBytes, TString url, TString data, IHTTPGateway::THeaders headers, size_t offset, size_t expectedSize, IHTTPGateway::TOnResult callback)
+        : TEasyCurl(counter, downloadedBytes, url, headers, offset, !data.empty()), ExpectedSize(expectedSize), Data(std::move(data)), Input(Data), Output(Buffer)
     {
-        Output.Reserve(expectedSize);
+        Output.Reserve(ExpectedSize);
         Callbacks.emplace(std::move(callback));
     }
 
-    static TPtr Make(const NMonitoring::TDynamicCounters::TCounterPtr&  counter, const NMonitoring::TDynamicCounters::TCounterPtr& downloadedBytes, TString url, TString data, IHTTPGateway::THeaders headers, std::size_t offset, std::size_t expectedSize, IHTTPGateway::TOnResult callback) {
+    static TPtr Make(const NMonitoring::TDynamicCounters::TCounterPtr&  counter, const NMonitoring::TDynamicCounters::TCounterPtr& downloadedBytes, TString url, TString data, IHTTPGateway::THeaders headers, size_t offset, size_t expectedSize, IHTTPGateway::TOnResult callback) {
         return std::make_shared<TEasyCurlBuffer>(counter, downloadedBytes, std::move(url), std::move(data), std::move(headers), offset, expectedSize, std::move(callback));
     }
-private:
-    bool AddCallback(IHTTPGateway::TOnResult callback) final {
+
+    size_t GetExpectedSize() const {
+        return ExpectedSize;
+    }
+
+    // return true if callback successfully added to this work
+    bool AddCallback(IHTTPGateway::TOnResult callback) {
         const std::unique_lock lock(SyncCallbacks);
         if (Callbacks.empty())
             return false;
         Callbacks.emplace(std::move(callback));
         return true;
     }
-
+private:
     void Fail(const TIssue& error) final  {
         TIssues issues{error};
         const std::unique_lock lock(SyncCallbacks);
@@ -147,6 +150,7 @@ private:
         return Input.Read(buffer, size * nmemb);
     };
 
+    const size_t ExpectedSize;
     const TString Data;
     TString Buffer;
     TStringInput Input;
@@ -158,18 +162,35 @@ private:
 
 class TEasyCurlStream : public TEasyCurl {
 public:
-    TEasyCurlStream(const NMonitoring::TDynamicCounters::TCounterPtr&  counter, const NMonitoring::TDynamicCounters::TCounterPtr& downloadedBytes, TString url, IHTTPGateway::THeaders headers, std::size_t offset, std::size_t expectedSize, IHTTPGateway::TOnNewDataPart onNewData, IHTTPGateway::TOnDownloadFinish onFinish)
-        : TEasyCurl(counter, downloadedBytes, url, headers, offset, expectedSize, false), OnNewData(std::move(onNewData)), OnFinish(std::move(onFinish))
-    {
+    using TPtr = std::shared_ptr<TEasyCurlStream>;
+    using TWeakPtr = std::weak_ptr<TEasyCurlStream>;
+
+    TEasyCurlStream(const NMonitoring::TDynamicCounters::TCounterPtr&  counter, const NMonitoring::TDynamicCounters::TCounterPtr& downloadedBytes, TString url, IHTTPGateway::THeaders headers, size_t offset, IHTTPGateway::TOnNewDataPart onNewData, IHTTPGateway::TOnDownloadFinish onFinish)
+        : TEasyCurl(counter, downloadedBytes, url, headers, offset, false), OnNewData(std::move(onNewData)), OnFinish(std::move(onFinish)), Counter(std::make_shared<std::atomic_size_t>(0ULL))
+    {}
+
+    static TPtr Make(const NMonitoring::TDynamicCounters::TCounterPtr&  counter, const NMonitoring::TDynamicCounters::TCounterPtr& downloadedBytes, TString url, IHTTPGateway::THeaders headers, size_t offset, IHTTPGateway::TOnNewDataPart onNewData, IHTTPGateway::TOnDownloadFinish onFinish) {
+        return std::make_shared<TEasyCurlStream>(counter, downloadedBytes, std::move(url), std::move(headers), offset, std::move(onNewData), std::move(onFinish));
     }
 
-    static TPtr Make(const NMonitoring::TDynamicCounters::TCounterPtr&  counter, const NMonitoring::TDynamicCounters::TCounterPtr& downloadedBytes, TString url, IHTTPGateway::THeaders headers, std::size_t offset, std::size_t expectedSize, IHTTPGateway::TOnNewDataPart onNewData, IHTTPGateway::TOnDownloadFinish onFinish) {
-        return std::make_shared<TEasyCurlStream>(counter, downloadedBytes, std::move(url), std::move(headers), offset, expectedSize, std::move(onNewData), std::move(onFinish));
+    enum class EAction : i8 {
+        Stop = -1,
+        None = 0,
+        Work = 1
+    };
+
+    EAction GetAction(size_t buffersSize) {
+        if (Working != Counter->load() < buffersSize) {
+            if (Working = !Working)
+                SkipTo(Position);
+            return Working ? EAction::Work : EAction::Stop;
+        }
+
+        return EAction::None;
     }
 private:
-    bool AddCallback(IHTTPGateway::TOnResult) final { return false; }
-
     void Fail(const TIssue& error) final  {
+        Working = false;
         return OnFinish(TIssues{error});
     }
 
@@ -177,12 +198,14 @@ private:
         if (CURLE_OK != result)
             return Fail(TIssue(curl_easy_strerror(result)));
 
+        Working = false;
         return OnFinish(std::nullopt);
     }
 
-    size_t  Write(void* contents, size_t size, size_t nmemb) final {
+    size_t Write(void* contents, size_t size, size_t nmemb) final {
         const auto realsize = size * nmemb;
-        OnNewData(IHTTPGateway::TContent(TString(static_cast<char*>(contents), realsize)));
+        Position += realsize;
+        OnNewData(IHTTPGateway::TCountedContent(TString(static_cast<char*>(contents), realsize), Counter));
         return realsize;
     };
 
@@ -190,9 +213,12 @@ private:
 
     const IHTTPGateway::TOnNewDataPart OnNewData;
     const IHTTPGateway::TOnDownloadFinish OnFinish;
+    const std::shared_ptr<std::atomic_size_t> Counter;
+    bool Working = false;
+    size_t Position = 0ULL;
 };
 
-using TKeyType = std::tuple<TString, std::size_t, IHTTPGateway::THeaders, TString, IRetryPolicy<long>::TPtr>;
+using TKeyType = std::tuple<TString, size_t, IHTTPGateway::THeaders, TString, IRetryPolicy<long>::TPtr>;
 
 class TKeyHash {
 public:
@@ -222,7 +248,7 @@ public:
         : Counters(std::move(counters))
         , Rps(Counters->GetCounter("Requests", true))
         , InFlight(Counters->GetCounter("InFlight"))
-        , StraightInFlight(Counters->GetCounter("StraightInFlight"))
+        , InFlightStreams(Counters->GetCounter("InFlightStreams"))
         , MaxInFlight(Counters->GetCounter("MaxInFlight"))
         , AllocatedMemory(Counters->GetCounter("AllocatedMemory"))
         , MaxAllocatedMemory(Counters->GetCounter("MaxAllocatedMemory"))
@@ -242,6 +268,10 @@ public:
                 MaxSimulatenousDownloadsSize = httpGatewaysCfg->GetMaxSimulatenousDownloadsSize();
             }
             MaxAllocatedMemory->Set(MaxSimulatenousDownloadsSize);
+
+            if (httpGatewaysCfg->HasBuffersSizePerStream()) {
+                BuffersSizePerStream = httpGatewaysCfg->GetBuffersSizePerStream();
+            }
         }
 
         TaskScheduler.Start();
@@ -253,8 +283,9 @@ public:
         Thread.join();
     }
 private:
-    std::size_t MaxHandlers = 1024U;
-    std::size_t MaxSimulatenousDownloadsSize = 8_GB;
+    size_t MaxHandlers = 1024U;
+    size_t MaxSimulatenousDownloadsSize = 8_GB;
+    size_t BuffersSizePerStream = CURL_MAX_WRITE_SIZE << 1U;
 
     static void Perform(const TWeakPtr& weak) {
         OutputSize.store(0ULL);
@@ -310,7 +341,25 @@ private:
 
     size_t FillHandlers() {
         const std::unique_lock lock(Sync);
-        const ui64 topExpectedSize = Await.empty() ? 0 : Await.front()->GetExpectedSize(); 
+
+        for (auto it = Streams.cbegin(); Streams.cend() != it;) {
+            if (const auto& stream = it->lock()) {
+                switch (stream->GetAction(BuffersSizePerStream)) {
+                    case TEasyCurlStream::EAction::Work:
+                        curl_multi_add_handle(Handle, stream->GetHandle());
+                        break;
+                    case TEasyCurlStream::EAction::Stop:
+                        curl_multi_remove_handle(Handle, stream->GetHandle());
+                        break;
+                    case TEasyCurlStream::EAction::None:
+                        break;
+                }
+                ++it;
+            } else
+                it = Streams.erase(it);
+        }
+
+        const ui64 topExpectedSize = Await.empty() ? 0 : Await.front()->GetExpectedSize();
         AwaitQueueTopExpectedSize->Set(topExpectedSize);
         while (!Await.empty() && Allocated.size() < MaxHandlers && AllocatedSize + Await.front()->GetExpectedSize() <= MaxSimulatenousDownloadsSize) {
             AllocatedSize += Await.front()->GetExpectedSize();
@@ -334,14 +383,16 @@ private:
                 easy = std::move(it->second);
                 curl_easy_getinfo(easy->GetHandle(), CURLINFO_RESPONSE_CODE, &httpResponseCode);
 
-                if (const auto stateIt = Easy2RetryState.find(easy); stateIt != Easy2RetryState.end()) {
-                    if (const auto& nextRetryDelay = stateIt->second->GetNextRetryDelay(httpResponseCode)) {
-                        Y_VERIFY(isRetry = TaskScheduler.Add(new THttpGatewayTask(easy, Singleton), *nextRetryDelay));
-                    } else {
-                        Easy2RetryState.erase(stateIt);
+                if (const auto& buffer = std::dynamic_pointer_cast<TEasyCurlBuffer>(easy)) {
+                    if (const auto stateIt = Easy2RetryState.find(buffer); stateIt != Easy2RetryState.cend()) {
+                        if (const auto& nextRetryDelay = stateIt->second->GetNextRetryDelay(httpResponseCode)) {
+                            Y_VERIFY(isRetry = TaskScheduler.Add(new THttpGatewayTask(buffer, Singleton), *nextRetryDelay));
+                        } else {
+                            Easy2RetryState.erase(stateIt);
+                        }
                     }
+                    AllocatedSize -= buffer->GetExpectedSize();
                 }
-                AllocatedSize -= easy->GetExpectedSize();
                 Allocated.erase(it);
             }
 
@@ -360,7 +411,6 @@ private:
 
             for (const auto& item : Allocated) {
                 works.emplace(std::move(item.second));
-                AllocatedSize -= works.top()->GetExpectedSize();
             }
 
             AllocatedSize = 0ULL;
@@ -379,7 +429,7 @@ private:
     void Download(
         TString url,
         THeaders headers,
-        std::size_t expectedSize,
+        size_t expectedSize,
         TOnResult callback,
         TString data,
         IRetryPolicy<long>::TPtr retryPolicy) final
@@ -393,7 +443,6 @@ private:
         }
         const std::unique_lock lock(Sync);
         auto& entry = Requests[TKeyType(url, 0U, headers, data, retryPolicy)];
-        StraightInFlight->Set(Requests.size());
         if (const auto& easy = entry.lock())
             if (easy->AddCallback(callback))
                 return;
@@ -408,25 +457,27 @@ private:
     void Download(
         TString url,
         THeaders headers,
-        std::size_t offset,
+        size_t offset,
         TOnNewDataPart onNewData,
         TOnDownloadFinish onFinish) final
     {
-        constexpr auto buffersSize = CURL_MAX_WRITE_SIZE << 4U;
-        auto easy = TEasyCurlStream::Make(InFlight, DownloadedBytes, std::move(url), std::move(headers), offset, buffersSize, std::move(onNewData), std::move(onFinish));
+
+        auto stream = TEasyCurlStream::Make(InFlightStreams, DownloadedBytes, std::move(url), std::move(headers), offset, std::move(onNewData), std::move(onFinish));
         const std::unique_lock lock(Sync);
-        Await.emplace(std::move(easy));
-        Wakeup(buffersSize);
+        const auto handle = stream->GetHandle();
+        Streams.emplace_back(stream);
+        Allocated.emplace(handle, std::move(stream));
+        Wakeup(0ULL);
     }
 
-    void OnRetry(TEasyCurl::TPtr easy) {
+    void OnRetry(TEasyCurlBuffer::TPtr easy) {
         const std::unique_lock lock(Sync);
-        const std::size_t expectedSize = easy->GetExpectedSize();
+        const size_t expectedSize = easy->GetExpectedSize();
         Await.emplace(std::move(easy));
         Wakeup(expectedSize);
     }
 
-    void Wakeup(std::size_t expectedSize) {
+    void Wakeup(size_t expectedSize) {
         AwaitQueue->Set(Await.size());
         if (Allocated.size() < MaxHandlers && AllocatedSize + expectedSize + OutputSize.load() <= MaxSimulatenousDownloadsSize) {
             curl_multi_wakeup(Handle);
@@ -436,7 +487,7 @@ private:
     class THttpGatewayTask: public TTaskScheduler::IRepeatedTask {
     public:
         THttpGatewayTask(
-            TEasyCurl::TPtr easy,
+            TEasyCurlBuffer::TPtr easy,
             THTTPMultiGateway::TWeakPtr gateway)
             : Easy(easy)
             , Gateway(gateway)
@@ -450,23 +501,24 @@ private:
             return false;
         }
     private:
-        TEasyCurl::TPtr Easy;
+        TEasyCurlBuffer::TPtr Easy;
         THTTPMultiGateway::TWeakPtr Gateway;
     };
 
 private:
     CURLM* Handle = nullptr;
 
-    std::queue<TEasyCurl::TPtr> Await;
+    std::queue<TEasyCurlBuffer::TPtr> Await;
+    std::vector<TEasyCurlStream::TWeakPtr> Streams;
 
     std::unordered_map<CURL*, TEasyCurl::TPtr> Allocated;
-    std::unordered_map<TKeyType, TEasyCurl::TWeakPtr, TKeyHash> Requests;
-    std::unordered_map<TEasyCurl::TPtr, IRetryPolicy<long>::IRetryState::TPtr> Easy2RetryState;
+    std::unordered_map<TKeyType, TEasyCurlBuffer::TWeakPtr, TKeyHash> Requests;
+    std::unordered_map<TEasyCurlBuffer::TPtr, IRetryPolicy<long>::IRetryState::TPtr> Easy2RetryState;
 
     std::mutex Sync;
     std::thread Thread;
 
-    std::size_t AllocatedSize = 0ULL;
+    size_t AllocatedSize = 0ULL;
     static std::atomic_size_t OutputSize;
 
     static std::mutex CreateSync;
@@ -475,7 +527,7 @@ private:
     const NMonitoring::TDynamicCounterPtr Counters;
     const NMonitoring::TDynamicCounters::TCounterPtr Rps;
     const NMonitoring::TDynamicCounters::TCounterPtr InFlight;
-    const NMonitoring::TDynamicCounters::TCounterPtr StraightInFlight; // doesn't consider merged requests which use one curl
+    const NMonitoring::TDynamicCounters::TCounterPtr InFlightStreams;
     const NMonitoring::TDynamicCounters::TCounterPtr MaxInFlight;
     const NMonitoring::TDynamicCounters::TCounterPtr AllocatedMemory;
     const NMonitoring::TDynamicCounters::TCounterPtr MaxAllocatedMemory;
@@ -494,44 +546,61 @@ THTTPMultiGateway::TWeakPtr THTTPMultiGateway::Singleton;
 
 }
 
-IHTTPGateway::TContent::TContent(TString&& data, long httpResponseCode)
+IHTTPGateway::TContentBase::TContentBase(TString&& data)
     : TString(std::move(data))
-    , HttpResponseCode(httpResponseCode)
 {
     if (!empty()) {
         THTTPMultiGateway::OutputSize.fetch_add(size());
     }
 }
 
-IHTTPGateway::TContent::TContent(const TString& data, long httpResponseCode)
+IHTTPGateway::TContentBase::TContentBase(const TString& data)
     : TString(data)
-    , HttpResponseCode(httpResponseCode)
 {
     if (!empty()) {
         THTTPMultiGateway::OutputSize.fetch_add(size());
     }
 }
 
-IHTTPGateway::TContent::TContent(TString&& data)
-    : TContent(std::move(data), 0)
-{}
-
-IHTTPGateway::TContent::TContent(const TString& data)
-    : TContent(data, 0)
-{}
-
-TString IHTTPGateway::TContent::Extract() {
+IHTTPGateway::TContentBase::~TContentBase()
+{
     if (!empty()) {
         THTTPMultiGateway::OutputSize.fetch_sub(size());
     }
-    return std::move(*this);
 }
 
-IHTTPGateway::TContent::~TContent()
-{
+TString IHTTPGateway::TContentBase::Extract() {
     if (!empty()) {
         THTTPMultiGateway::OutputSize.fetch_sub(size());
     }
+    return std::move(*this);
+}
+
+IHTTPGateway::TContent::TContent(TString&& data, long httpResponseCode)
+    : TContentBase(std::move(data))
+    , HttpResponseCode(httpResponseCode)
+{}
+
+IHTTPGateway::TContent::TContent(const TString& data, long httpResponseCode)
+    : TContentBase(data)
+    , HttpResponseCode(httpResponseCode)
+{}
+
+
+IHTTPGateway::TCountedContent::TCountedContent(TString&& data, const std::shared_ptr<std::atomic_size_t>& counter)
+    : TContentBase(std::move(data)), Counter(counter)
+{
+    Counter->fetch_add(size());
+}
+
+IHTTPGateway::TCountedContent::~TCountedContent()
+{
+    Counter->fetch_sub(size());
+}
+
+TString IHTTPGateway::TCountedContent::Extract() {
+    Counter->fetch_sub(size());
+    return TContentBase::Extract();
 }
 
 IHTTPGateway::TPtr
@@ -546,5 +615,4 @@ IHTTPGateway::Make(const THttpGatewayConfig* httpGatewaysCfg, NMonitoring::TDyna
     return gateway;
 }
 
-
 }
diff --git a/ydb/library/yql/providers/common/http_gateway/yql_http_gateway.h b/ydb/library/yql/providers/common/http_gateway/yql_http_gateway.h
index 7b745323b57..d5979bcce19 100644
--- a/ydb/library/yql/providers/common/http_gateway/yql_http_gateway.h
+++ b/ydb/library/yql/providers/common/http_gateway/yql_http_gateway.h
@@ -8,6 +8,7 @@
 #include <library/cpp/retry/retry_policy.h>
 #include <library/cpp/threading/task_scheduler/task_scheduler.h>
 
+#include <atomic>
 #include <variant>
 #include <functional>
 
@@ -24,28 +25,36 @@ public:
         const THttpGatewayConfig* httpGatewaysCfg = nullptr,
         NMonitoring::TDynamicCounterPtr counters = MakeIntrusive<NMonitoring::TDynamicCounters>());
 
-    class TContent : private TString {
-    friend class TEasyCurl;
-    public:
-        TContent(TString&& data, long httpResponseCode);
-        TContent(const TString& data, long httpResponseCode);
-        TContent(TString&& data);
-        TContent(const TString& data);
+    class TContentBase : protected TString {
+    protected:
+        TContentBase(TString&& data);
+        TContentBase(const TString& data);
 
-        TString Extract();
-        ~TContent();
-
-        TContent(TContent&&) = default;
-        TContent& operator=(TContent&&) = default;
+        TContentBase(TContentBase&&) = default;
+        TContentBase& operator=(TContentBase&&) = default;
 
+        ~TContentBase();
+        TString Extract();
+    public:
         using TString::size;
         using TString::data;
 
         inline operator std::string_view() const { return { data(), size() }; }
     private:
-        TContent(const TContent&) = delete;
-        TContent& operator=(const TContent&) = delete;
+        TContentBase(const TContentBase&) = delete;
+        TContentBase& operator=(const TContentBase&) = delete;
+    };
+
+    class TContent : public TContentBase {
+    friend class TEasyCurl;
+    public:
+        TContent(TString&& data, long httpResponseCode = 0LL);
+        TContent(const TString& data, long httpResponseCode = 0LL);
+
+        TContent(TContent&& src) = default;
+        TContent& operator=(TContent&& src) = default;
 
+        using TContentBase::Extract;
     public:
         long HttpResponseCode;
     };
@@ -63,7 +72,20 @@ public:
         IRetryPolicy</*http response code*/long>::TPtr RetryPolicy = IRetryPolicy<long>::GetNoRetryPolicy()
     ) = 0;
 
-    using TOnNewDataPart = std::function<void(TContent&&)>;
+    class TCountedContent : public TContentBase {
+    public:
+        TCountedContent(TString&& data, const std::shared_ptr<std::atomic_size_t>& counter);
+        ~TCountedContent();
+
+        TCountedContent(TCountedContent&&) = default;
+        TCountedContent& operator=(TCountedContent&& src) = default;
+
+        TString Extract();
+    private:
+        const std::shared_ptr<std::atomic_size_t> Counter;
+    };
+
+    using TOnNewDataPart = std::function<void(TCountedContent&&)>;
     using TOnDownloadFinish = std::function<void(std::optional<TIssues>)>;
 
     virtual void Download(
diff --git a/ydb/library/yql/providers/common/proto/gateways_config.proto b/ydb/library/yql/providers/common/proto/gateways_config.proto
index 6155aa76603..2910c9c2487 100644
--- a/ydb/library/yql/providers/common/proto/gateways_config.proto
+++ b/ydb/library/yql/providers/common/proto/gateways_config.proto
@@ -55,6 +55,7 @@ enum ETokenType {
 message THttpGatewayConfig {
     optional uint32 MaxInFlightCount = 1;
     optional uint64 MaxSimulatenousDownloadsSize = 2;
+    optional uint32 BuffersSizePerStream = 3;
 }
 
 /////////////////////////////// YT ///////////////////////////////
diff --git a/ydb/library/yql/providers/s3/actors/yql_s3_read_actor.cpp b/ydb/library/yql/providers/s3/actors/yql_s3_read_actor.cpp
index 8c9b01ccf32..3c47e5d9632 100644
--- a/ydb/library/yql/providers/s3/actors/yql_s3_read_actor.cpp
+++ b/ydb/library/yql/providers/s3/actors/yql_s3_read_actor.cpp
@@ -72,6 +72,11 @@ struct TEvPrivate {
         const size_t PathIndex;
     };
 
+    struct TEvDataPart : public TEventLocal<TEvDataPart, EvReadResult> {
+        TEvDataPart(IHTTPGateway::TCountedContent&& data) : Result(std::move(data)) {}
+        IHTTPGateway::TCountedContent Result;
+    };
+
     struct TEvReadFinished : public TEventLocal<TEvReadFinished, EvReadFinished> {};
 
     struct TEvReadError : public TEventLocal<TEvReadError, EvReadError> {
@@ -281,7 +286,7 @@ private:
     class TReadBufferFromStream : public NDB::ReadBuffer {
     public:
         TReadBufferFromStream(TS3ReadCoroImpl* coro)
-            : NDB::ReadBuffer(nullptr, 0ULL), Coro(coro), Value(TString())
+            : NDB::ReadBuffer(nullptr, 0ULL), Coro(coro)
         {}
     private:
         bool nextImpl() final {
@@ -294,18 +299,18 @@ private:
         }
 
         TS3ReadCoroImpl *const Coro;
-        IHTTPGateway::TContent Value;
+        TString Value;
     };
 public:
     TS3ReadCoroImpl(ui64 inputIndex, const NActors::TActorId& sourceActorId, const NActors::TActorId& computeActorId, const TReadSpec::TPtr& readSpec)
         : TActorCoroImpl(256_KB), InputIndex(inputIndex), ReadSpec(readSpec), SourceActorId(sourceActorId), ComputeActorId(computeActorId)
     {}
 
-    bool Next(IHTTPGateway::TContent& value) {
+    bool Next(TString& value) {
         if (Finished)
             return false;
 
-        const auto ev = WaitForSpecificEvent<TEvPrivate::TEvReadResult, TEvPrivate::TEvReadError, TEvPrivate::TEvReadFinished>();
+        const auto ev = WaitForSpecificEvent<TEvPrivate::TEvDataPart, TEvPrivate::TEvReadError, TEvPrivate::TEvReadFinished>();
         switch (const auto etype = ev->GetTypeRewrite()) {
             case TEvPrivate::TEvReadFinished::EventType:
                 Finished = true;
@@ -313,8 +318,8 @@ public:
             case TEvPrivate::TEvReadError::EventType:
                 Send(ComputeActorId, new IDqComputeActorAsyncInput::TEvAsyncInputError(InputIndex, ev->Get<TEvPrivate::TEvReadError>()->Error, true));
                 return false;
-            case TEvPrivate::TEvReadResult::EventType:
-                value = std::move(ev->Get<TEvPrivate::TEvReadResult>()->Result);
+            case TEvPrivate::TEvDataPart::EventType:
+                value = ev->Get<TEvPrivate::TEvDataPart>()->Result.Extract();
                 Send(ComputeActorId, new IDqComputeActorAsyncInput::TEvNewAsyncInputDataArrived(InputIndex));
                 return true;
             default:
@@ -380,10 +385,10 @@ public:
         , RetryStuff(std::make_shared<TRetryStuff>(std::move(gateway), url + path, headers, retryConfig, expectedSize))
     {}
 private:
-    static void OnNewData(TActorSystem* actorSystem, const TActorId& self, const TActorId& parent, const TRetryStuff::TPtr& retryStuff, IHTTPGateway::TContent&& data) {
+    static void OnNewData(TActorSystem* actorSystem, const TActorId& self, const TActorId& parent, const TRetryStuff::TPtr& retryStuff, IHTTPGateway::TCountedContent&& data) {
         retryStuff->Offset += data.size();
         retryStuff->RetryParams.Reset();
-        actorSystem->Send(new IEventHandle(self, parent, new TEvPrivate::TEvReadResult(std::move(data))));
+        actorSystem->Send(new IEventHandle(self, parent, new TEvPrivate::TEvDataPart(std::move(data))));
     }
 
     static void OnDownloadFinished(TActorSystem* actorSystem, const TActorId& self, const TActorId& parent, const TRetryStuff::TPtr& retryStuff, std::optional<TIssues> result) {