Multiple commands using JSch
For executing multiple commands in sequence, you can create a command string like below: String script =”pbrun su – user; cd /home/scripts;./sample_script.sh” Execute it and pass this string to your method above.
channel
Do buffered channels maintain order?
“Are you guaranteed that B will read data In the same order that A put it into the channel?” Yes. The order of data is guaranteed. But the delivery is guaranteed only for unbuffered channels, not buffered. (see second section of this answer) You can see the idea of channels illustrated in “The Nature Of … Read more
anonymous struct and empty struct
Note that one interesting aspect of using struct{} for the type pushed to a channel (as opposed to int or bool), is that the size of an empty struct is… 0! See the recent article “The empty struct” (March 2014) by Dave Cheney. You can create as many struct{} as you want (struct{}{}) to push … Read more
What is channel buffer size?
The buffer size is the number of elements that can be sent to the channel without the send blocking. By default, a channel has a buffer size of 0 (you get this with make(chan int)). This means that every single send will block until another goroutine receives from the channel. A channel of buffer size … Read more
Closing channel of unknown length
Once a channel is closed, you can’t send further values on it else it panics. This is what you experience. This is because you start multiple goroutines that use the same channel and they send values on it. And you close the channel in each of it. And since they are not synchronized, once the … Read more
How to collect values from N goroutines executed in a specific order?
Goroutines run concurrently, independently, so without explicit synchronization you can’t predict execution and completion order. So as it is, you can’t pair returned numbers with the input numbers. You can either return more data (e.g. the input number and the output, wrapped in a struct for example), or pass pointers to the worker functions (launched … Read more
How to calculate the average rgb color values of a bitmap
The fastest way is by using unsafe code: BitmapData srcData = bm.LockBits( new Rectangle(0, 0, bm.Width, bm.Height), ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb); int stride = srcData.Stride; IntPtr Scan0 = srcData.Scan0; long[] totals = new long[] {0,0,0}; int width = bm.Width; int height = bm.Height; unsafe { byte* p = (byte*) (void*) Scan0; for (int y = 0; y … Read more
Goroutine does not execute if time.Sleep included
When the main function ends, the program ends with it. It does not wait for other goroutines to finish. Quoting from the Go Language Specification: Program Execution: Program execution begins by initializing the main package and then invoking the function main. When that function invocation returns, the program exits. It does not wait for other … Read more
Message channels one or many?
In each child context, you can add a header enricher to set a custom header to the URL from the adapter; with the output channel being the shared channel to the shared service. In the service, use void foo(Message emailMessage, @Header(“myHeader”) String url) I would generally recommend using a single service unless the service needs … Read more
Terminating function execution if a context is cancelled
Function calls and goroutines cannot be terminated from the caller, the functions and goroutines have to support the cancellation, often via a context.Context value or a done channel. In either case, the functions are responsible to check / monitor the context, and if cancel is requested (when the Context’s done channel is closed), return early. … Read more