commit | eda5a4db1e88e484d0c45401c345cbc199d633fd | [log] [tgz] |
---|---|---|
author | Nathaniel Manista <nathaniel@google.com> | Sat Sep 09 15:52:11 2017 +0000 |
committer | Nathaniel Manista <nathaniel@google.com> | Sat Sep 09 21:42:38 2017 +0000 |
tree | e9ad2c76518d81854aa1585b0704a1306ba3c473 | |
parent | 8380090f953c193f9c511ee844c3099d3f7e0766 [diff] |
Fix metadata memory leak The gRPC Core has two styles for passing metadata: as an integer count along with a grpc_metadata* pointer, which is used for passing metadata into the core, and as a grpc_metadata_array, which is used for passing metadata out of the core. The Cython layer of gRPC Python was using a single data structure wrapping grpc_metadata_array for both purposes, but this was complex because the core manages the slices contained in grpc_metadata_array objects (at least those of which it is aware), so the Cython layer had to keep track of whether or not the core was aware of the slices it was using (and it was also defective, leaking slices). This is solved by realigning with the Cython layer’s intended design of mirroring as closely as possible in Python the gRPC Core API: we use one structure for passing metadata into the core (what is now called cygrpc.Metadata) and second, different structure for receiving metadata out of the core (what was called cygrpc.Metadata but is now cygrpc.MetadataArray, reflecting that it wraps the core’s grpc_metadata_array). All bug fixes should contain added tests preventing regression but this doesn't because I don't know at this time how to write a does-not-leak test for Python that fits well into our existing body of tests. Phooey. Thanks to Dominik Janků (djanku@email.cz) for investigation and an earlier draft of a solution.
Copyright 2015 Google Inc.
You can find more detailed documentation and examples in the doc and examples directories respectively.
See INSTALL for installation instructions for various platforms.
See tools/run_tests for more guidance on how to run various test suites (e.g. unit tests, interop tests, benchmarks)
See Performance dashboard for the performance numbers for the latest released version.
This repository contains source code for gRPC libraries for multiple languages written on top of shared C core library src/core.
Libraries in different languages may be in different states of development. We are seeking contributions for all of these libraries.
Language | Source | Status |
---|---|---|
Shared C [core library] | src/core | 1.0 |
C++ | src/cpp | 1.0 |
Ruby | src/ruby | 1.0 |
NodeJS | src/node | 1.0 |
Python | src/python | 1.0 |
PHP | src/php | 1.0 |
C# | src/csharp | 1.0 |
Objective-C | src/objective-c | 1.0 |
Java source code is in the grpc-java repository. Go source code is in the grpc-go repository.
See MANIFEST.md for a listing of top-level items in the repository.
Remote Procedure Calls (RPCs) provide a useful abstraction for building distributed applications and services. The libraries in this repository provide a concrete implementation of the gRPC protocol, layered over HTTP/2. These libraries enable communication between clients and servers using any combination of the supported languages.
Developers using gRPC typically start with the description of an RPC service (a collection of methods), and generate client and server side interfaces which they use on the client-side and implement on the server side.
By default, gRPC uses Protocol Buffers as the Interface Definition Language (IDL) for describing both the service interface and the structure of the payload messages. It is possible to use other alternatives if desired.
Starting from an interface definition in a .proto file, gRPC provides Protocol Compiler plugins that generate Client- and Server-side APIs. gRPC users typically call into these APIs on the Client side and implement the corresponding API on the server side.
Synchronous RPC calls, that block until a response arrives from the server, are the closest approximation to the abstraction of a procedure call that RPC aspires to.
On the other hand, networks are inherently asynchronous and in many scenarios, it is desirable to have the ability to start RPCs without blocking the current thread.
The gRPC programming surface in most languages comes in both synchronous and asynchronous flavors.
gRPC supports streaming semantics, where either the client or the server (or both) send a stream of messages on a single RPC call. The most general case is Bidirectional Streaming where a single gRPC call establishes a stream where both the client and the server can send a stream of messages to each other. The streamed messages are delivered in the order they were sent.
The gRPC protocol specifies the abstract requirements for communication between clients and servers. A concrete embedding over HTTP/2 completes the picture by fleshing out the details of each of the required operations.
A gRPC RPC comprises of a bidirectional stream of messages, initiated by the client. In the client-to-server direction, this stream begins with a mandatory Call Header
, followed by optional Initial-Metadata
, followed by zero or more Payload Messages
. The server-to-client direction contains an optional Initial-Metadata
, followed by zero or more Payload Messages
terminated with a mandatory Status
and optional Status-Metadata
(a.k.a.,Trailing-Metadata
).
The abstract protocol defined above is implemented over HTTP/2. gRPC bidirectional streams are mapped to HTTP/2 streams. The contents of Call Header
and Initial Metadata
are sent as HTTP/2 headers and subject to HPACK compression. Payload Messages
are serialized into a byte stream of length prefixed gRPC frames which are then fragmented into HTTP/2 frames at the sender and reassembled at the receiver. Status
and Trailing-Metadata
are sent as HTTP/2 trailing headers (a.k.a., trailers).
gRPC inherits the flow control mechanisms in HTTP/2 and uses them to enable fine-grained control of the amount of memory used for buffering in-flight messages.