Set Windows command-line terminal title in Python
On Windows, a simple console command will suffice: from os import system system(“title ” + myCoolTitle) Nice and easy.
low-latency
Why is hibernate batching / order_inserts / order_updates disabled by default?
Generally, setting batch size to reasonable size and order_insert, order_updates to true can significantly improve performance. In all my projects, I use this configuration as basis: hibernate.jdbc.batch_size = 100 hibernate.order_inserts = true hibernate.order_updates = true hibernate.jdbc.fetch_size = 400 But, yes – there can be memory impact when using batching. But this depends on jdbc driver. … Read more
What is the difference between latency and response time?
One way of looking at this is to say that transport latency + processing time = response time. Transport latency is the time it takes for a request/response to be transmitted to/from the processing component. Then you need to add the time it takes to process the request. As an example, say that 5 people … Read more
What is your development checklist for Java low-latency application?
Although immutability is good, it is not necessarily going to improve latency. Ensuring low-latency is likely to be platform dependent. Other than general performance, GC tuning is very important. Reducing memory usage will help GC. In particular if you can reduce the number of middle-aged objects that need to get moved about – keep it … Read more
Why to use websocket and what is the advantage of using it?
Why use websocket over http? A webSocket is a continuous connection between client and server. That continuous connection allows the following: Data can be sent from server to client at any time, without the client even requesting it. This is often called server-push and is very valuable for applications where the client needs to know … Read more
How fast is state of the art HFT trading systems today?
I’m the CTO of a small company that makes and sells FPGA-based HFT systems. Building our systems on-top of the Solarflare Application Onload Engine (AOE) we have been consistently delivering latency from an “interesting” market event on the wire (10Gb/S UDP market data feed from ICE or CME) to the first byte of the resultant … Read more
Why does the JVM require warmup?
Which parts of the code should you warm up? Usually, you don’t have to do anything. However for a low latency application, you should warmup the critical path in your system. You should have unit tests, so I suggest you run those on start up to warmup up the code. Even once your code is … Read more
Node.js, Socket.io, Redis pub/sub high volume, low latency difficulties
I thought this was a reasonable question and had researched it briefly a while back. I spent a little time searching for examples that you may be able to pick up some helpful tips from. Examples I like to begin with straight forward examples: light im sample code Node.js + Redis Pub/Sub + socket.io demo … Read more
Why is returning a Java object reference so much slower than returning a primitive
TL;DR: You should not put BLIND trust into anything. First things first: it is important to verify the experimental data before jumping to the conclusions from them. Just claiming something is 3x faster/slower is odd, because you really need to follow up on the reason for the performance difference, not just trust the numbers. This … Read more
Approximate cost to access various caches and main memory?
Numbers everyone should know 0.5 ns – CPU L1 dCACHE reference 1 ns – speed-of-light (a photon) travel a 1 ft (30.5cm) distance 5 ns – CPU L1 iCACHE Branch mispredict 7 ns – CPU L2 CACHE reference 71 ns – CPU cross-QPI/NUMA best case on XEON E5-46* 100 ns – MUTEX lock/unlock 100 ns … Read more