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README.md
gRPC Debug Example
The debug example uses a Hello World style server whose response includes its hostname. It demonstrates usage of the AdminInterface and the grpcdebug commandline tool.
The example requires grpc-java to already be built. You are strongly encouraged to check out a git release tag, since there will already be a build of grpc available. Otherwise, you must follow COMPILING.
Build the example
-
Optional: Build the hello-world-debug example client. See the examples README
-
Build the debuggable server and client. From the
grpc-java/examples/examples-debug
directory run:
$ ../gradlew installDist
This creates the
scripts build/install/debug/bin/hostname-debuggable-server/bin/hostname-debuggable-server
that
runs the example.
To run the debug example, run:
$ ./build/install/debug/bin/hostname-debuggable-server/bin/hostname-debuggable-server
And in a different terminal window run the client.
Note: You can use the standard hello-world client with no debugging enabled and still see results on the server. However, if you want to get debug information about the client you need to run the hello-world-debuggable client.
Simple client
$ ../build/install/examples/bin/hello-world-client
debug enabled client
$ ./build/install/examples-debug/bin/hello-world-debuggable-client
Maven
If you prefer to use Maven:
-
Build the hello-world example client. See the examples README
-
Run in this directory:
$ mvn verify
$ # Run the server (from the examples-debug directory)
$ mvn exec:java -Dexec.mainClass=io.grpc.examples.debug.HostnameServer
$ # In another terminal run the client (from the examples directory)
$ cd ..
$ mvn exec:java -Dexec.mainClass=io.grpc.examples.helloworld.HelloWorldClient
Using grpcdebug
grpcdebug is a tool that has been created to access the metrics from the channelz and health services.
Installing the grpcdebug tool
The source code is located in a github project grpc-ecosystem/grpcdebug. You can either download [the latest built version] (https://github.com/grpc-ecosystem/grpcdebug/releases/latest) (recommended) or follow the README.md to build it yourself.
Running the grpcdebug tool
Usage
grpcdebug <target address> [flags] channelz <command> [argument]
Command | Argument | Description |
---|---|---|
channel | <channel id or URL> | Display channel states in a human readable way. |
channels | Lists client channels for the target application. | |
server | <server ID> | Displays server state in a human readable way. |
servers | Lists servers in a human readable way. | |
socket | <socket ID> | Displays socket states in a human readable way. |
subchannel | <id> | Display subchannel states in human readable way. |
Generally, you will start with either servers
or channels
and then work down
to the details
Getting overall server info
bin/grpcdebug/grpcdebug localhost:50051 channelz servers
This will show you the server ids with their activity
Server ID Listen Addresses Calls(Started/Succeeded/Failed) Last Call Started
2 [[::]:50051] 38/34/3 now
Getting details for a service
bin/grpcdebug/grpcdebug localhost:50051 channelz server 2
The output will include more communication details and will show socket ids for currently connected clients
Server Id: 2
Listen Addresses: [[::]:50051]
Calls Started: 33
Calls Succeeded: 29
Calls Failed: 3
Last Call Started: now
---
Socket ID Local->Remote Streams(Started/Succeeded/Failed) Messages(Sent/Received)
19 [::1]:50051->[::1]:39834 4/3/0 3/4
Displaying detailed info for a server side connection (socket)
bin/grpcdebug/grpcdebug localhost:50051 channelz socket 19
This will show a lot of gRPC internal information
Socket ID: 19
Address: [::1]:50051->[::1]:50094
Streams Started: 1
Streams Succeeded: 0
Streams Failed: 0
Messages Sent: 0
Messages Received: 1
Keep Alives Sent: 0
Last Local Stream Created:
Last Remote Stream Created: now
Last Message Sent Created:
Last Message Received Created: now
Local Flow Control Window: 65535
Remote Flow Control Window: 1048569
---
Socket Options Name Value
SO_LINGER [type.googleapis.com/grpc.channelz.v1.SocketOptionLinger]:{}
io.grpc.netty.shaded.io.netty.channel.epoll.EpollChannelOption#TCP_CORK false
WRITE_BUFFER_HIGH_WATER_MARK 65536
WRITE_BUFFER_LOW_WATER_MARK 32768
IP_TOS 0
io.grpc.netty.shaded.io.netty.channel.epoll.EpollChannelOption#TCP_KEEPCNT 9
SINGLE_EVENTEXECUTOR_PER_GROUP true
SO_SNDBUF 2626560
io.grpc.netty.shaded.io.netty.channel.epoll.EpollChannelOption#TCP_NOTSENT_LOWAT 0
WRITE_BUFFER_WATER_MARK WriteBufferWaterMark(low: 32768, high: 65536)
TCP_NODELAY true
SO_RCVBUF 131072
io.grpc.netty.shaded.io.netty.channel.epoll.EpollChannelOption#SO_BUSY_POLL 0
IP_TRANSPARENT false
SO_KEEPALIVE true
io.grpc.netty.shaded.io.netty.channel.epoll.EpollChannelOption#TCP_QUICKACK false
ALLOCATOR PooledByteBufAllocator(directByDefault: true)
TCP_FASTOPEN_CONNECT false
MESSAGE_SIZE_ESTIMATOR io.grpc.netty.shaded.io.netty.channel.DefaultMessageSizeEstimator@48d475b6
WRITE_SPIN_COUNT 16
SO_REUSEADDR true
CONNECT_TIMEOUT_MILLIS 30000
ALLOW_HALF_CLOSURE false
io.grpc.netty.shaded.io.netty.channel.epoll.EpollChannelOption#EPOLL_MODE EDGE_TRIGGERED
MAX_MESSAGES_PER_READ 16
io.grpc.netty.shaded.io.netty.channel.epoll.EpollChannelOption#TCP_KEEPIDLE 7200
AUTO_CLOSE true
io.grpc.netty.shaded.io.netty.channel.epoll.EpollChannelOption#TCP_KEEPINTVL 75
MAX_MESSAGES_PER_WRITE 2147483647
AUTO_READ true
TCP_MD5SIG null
RCVBUF_ALLOCATOR io.grpc.netty.shaded.io.netty.channel.AdaptiveRecvByteBufAllocator@360691a0
Displaying the list of gRPC client channels
Command
bin/grpcdebug/grpcdebug localhost:50051 channelz channels
Output
Channel ID Target State Calls(Started/Succeeded/Failed) Created Time
1 localhost:50051 READY 34/34/0
3 localhost:50051 READY 16/16/0
Note: If you have a simple server that doesn't use gRPC clients to contact other servers, then this table will be empty.
Displaying details of a gRPC client channel
Command
bin/grpcdebug/grpcdebug localhost:50051 channelz channel 3
Output
Channel ID: 3
Target: localhost:50051
State: READY
Calls Started: 16
Calls Succeeded: 16
Calls Failed: 0
Created Time:
---
Subchannel ID Target State Calls(Started/Succeeded/Failed) CreatedTime
10 [[[localhost/127.0.0.1:50051]/{}], [[localhost/0:0 READY 16/16/0
Displaying details of a gRPC client subchannel
Command
bin/grpcdebug/grpcdebug localhost:50051 channelz subchannel 10
Output
Subchannel ID: 10
Target: [[[localhost/127.0.0.1:50051]/{}], [[localhost/0:0:0:0:0:0:0:1:50051]/{}]]
State: READY
Calls Started: 16
Calls Succeeded: 16
Calls Failed: 0
Created Time:
---
Socket ID Local->Remote Streams(Started/Succeeded/Failed) Messages(Sent/Received)
11 127.0.0.1:48536->127.0.0.1:50051 16/16/0 12/12