I went through documentation of Passenger to find out how many application instances it can run with respect to hardware configuration. Documentation only talks about RAM
The optimal value depends on your system’s hardware and the server’s average load. You should experiment with different values. But generally speaking, the value should be at least equal to the number of CPUs (or CPU cores) that you have. If your system has 2 GB of RAM, then we recommend a value of 30. If your system is a Virtual Private Server (VPS) and has about 256 MB RAM, and is also running other services such as MySQL, then we recommend a value of 2.
It says minimum value can be number of CPU/CPU Cores we have. I have a VPS with one VCPU & 1GB RAM & my service provider has an option to just upgrade the RAM. I'm wondering how far I can just keep upgrading only RAM? How important it is to upgrade number of CPUs?
Quick Answer
Depends on what resources are the bottleneck for your app.
Long answer
You'll need to factor in a few things:
How much CPU time does your app need?
How much RAM does any given instance of your app use at peak load?
Does your app spend a lot of time doing IO intensive tasks? (ie: db and file reads/writes, network communication)
There can be other things to factor in, but your bottlenecks will probably be one of the above. If RAM is your main bottleneck, by all means use your newly available RAM. However, if it turns out that your app is being slowed down by CPU availability or flooded IO, no amount of RAM is going to speed things up.
On the topic of CPU cores; my understanding is that the main Apache process that runs Passenger is a single threaded process. Apache spawns new threads to handle concurrency on an as-needed basis. Each additional CPU core theoretically allows you to spawn x*n threads, where x is the number of threads you can optimally run under a single CPU core and n is the number of CPU cores available to Apache.
Disclaimer: I'm not very well read on Passenger internals; though this logic usually holds true for other kinds of Apache configurations.
Related
I have some upstream flask containers and the CPU usage hit 100% percent when i entertain some requests.
the system shows that the containers are using your CPU 100%.
My questions are:
If i limit the CPU usage on these containers, will they exit with zero error if they hit there allocated resources OR what are the disadvantages of limiting resources against docker containers?
which one is the better approach in terms of resource allocation to docker containers? (For 6 cpu cores)
a) Two containers running with default settings. (Use as much resources as the kernel can provide may be)
b) 4 containers can only use 1 CPU (--limit cpus ='1')
Please let me know if you want me elaborate more.
Thanks in Advance
Containers (and other Linux processes) that try to use more CPU cycles than they have been allocated will just get throttled: the Linux kernel will schedule other processes instead. Going over your CPU limit has no adverse consequences other than your process running slower.
For example, say your program starts 4 threads and each runs some intensive computation using a full core, but you're running this in a Docker container with --cpus=2. All four threads will run, but the combined program will be limited to 200% CPU, and the overall performance will be similar to if you had only launched 2 threads.
You will usually get better overall system utilization if you don't explicitly limit CPU utilization. If you are running 4 containers, and one of them is running the 4-thread computation job described above but the other three are idle, you will fully use the available system resources if you don't have limits.
If you do have a specific computationally intensive container, you may want to limit its CPU utilization to not starve out other processes. If you only have the one worker container and three Web server containers, consider limiting the worker to 3 or 3.5 CPUs on a 4-core system to guarantee some spare cycles for HTTP traffic. This is a tuning optimization, so look into it only if you're seeing a problem.
Note that CPU and memory work differently. You can't really use "too much" CPU, since if you wait there will always be more CPU cycles, but the kernel rations out what your process is able to run. On the other hand, memory is fixed, and your process will get killed if it goes over a memory limit.
Looks like the most powerful instance type you can have in Google App Engine is one with 2G memory. One of our Rails application reaches the memory limit quickly on higher load. Autoscaling helps but wondering if there is a way to add more power instances in GAE?
If not, how have you solved this problem?
yes, in App Engine Standard the higher tier is F4_HIGHMEM with 2048 MB of memory. You have 3 ways to scale up with standard:
Automatic: based on request rate, response latencies, and other application metrics.
Basic: creates dynamic instances when your application receives requests.
Manual: uses resident instances that continuously run the specified number of instances regardless of the load level.
Therefore, the question here would be how are you reaching this limit? How are you managing your memory? Take a look into your console metrics: memoryusage. A ladder graphs shown a bad usage of the memory. When deploying apps in the Cloud, you must have in mind that the usage of the resources bust be more accurate.
You can analyze and check if choosing an automatic scale based on Max concurrent Requests would be a good option for you to mitigate your issue with the memory.
This is for Standard, Flexible is managed different. You can specify from 0.9 to 6.5 GB per CPU core.
We're planning to evaluate and eventually potentially purchase perfino. I went quickly through the docs and cannot find the system requirements for the installation. Also I cannot find it's compatibility with JBoss 7.1. Can you provide details please?
There are no hard system requirements for disk space, it depends on the amount of business transactions that you're recording. All data will be consolidated, so the database reaches a maximum size after a while, but it's not possible to say what that size will be. Consolidation times can be configured in the general settings.
There are also no hard system requirements for CPU and physical memory. A low-end machine will have no problems monitoring 100 JVMs, but the exact details again depend on the amount of monitored business transactions.
JBoss 7.1 is supported. "Supported" means that web service and EJB calls can be tracked between JVMs, otherwise all application servers work with perfino.
I haven't found any official system requirements, but this is what we figured out experimentally.
We collect about 10,000 transactions a minute from 8 JVMs. We have a lot of distinct and long SQL queries. We use AWS machine with 2 VCPUs and 8GB RAM.
When the Perfino GUI is not being used, the CPU load is low. However, for the GUI to work properly, we had to modify perfino_service.vmoptions:
-Xmx6000m. Before that we had experienced multiple OutOfMemoryError in Perfino when filtering in the transactions view. After changing the memory settings, the GUI is running fine.
This means that you need a machine with about 8GB RAM. I guess this depends on the number of distinct transactions you collect. Our limit is high, at 30,000.
After 6 weeks of usage, there's 7GB of files in the perfino directory. Perfino can clear old recordings after a configurable time.
We have an ASP.NET project (40 or so Web forms, 50 tables, pretty standard IO stuff with care taken to minimize when possible) that will soon need to be deployed. There will be about 100 concurrent users on the system, but only about 20 at any one time will be pounding on it it. We'll be deploying it on Windows Server 2008, 32-bit initially.
When considering production server spec which should we worry more about, getting more cores and less memory (4 cores and 4mb, for example) or more memory and less cores (2 cores and 8mb)?
Would bumping up to Windows Server 64-bit help with memory utilization?
32-bit Windows Server can only address ~3gb of memory. Get 64-bit, 2 cores and 4gb. Or if money isn't an issue, get 8 cores and 24gb. The point is to never guess. If you guess you will be wrong. Monitor the memory pressure and cpu load, and buy more/upgrade as necessary. It's impossible, and foolish, to try to guess what will be the performance bottleneck. The only way is to measure, measure, measure and respond according to that.
One important piece of information that is not included is how much data the databases are going to be holding and how much each user will be utilizing. That will determine how much cache you're going to want, and whether it will all fit in cache or if you're going to be hitting disk a lot more.
Utilization? Only if you're shooting for >3.5GB of ram. And with 20 simultaneous active users, you're going to want all 4 cores and a sizable cache, because the last thing you want is one active users data being flushed from cache to load another active users data, only to have to hit the disk to get the first users data when they take their next action, sending another active users data from cache... (read: thrashing).
I have windows 2003 terminal servers, multi-core. I'm looking for a way to monitor individual CPU core usage on these servers. It is possible for an end-user to have a run-away process (e.g. Internet Explorer or Outlook). The core for that process may spike to near 100% leaving the other cores 'normal'. Thus, the overall CPU usage on the server is just the total of all the cores or if 7 of the cores on a 8 core server are idle and the 8th is running at 100% then 1/8 = 12.5% usage.
What utility can I use to monitor multiple servers ? If the CPU usage for a core is "high" what would I use to determine the offending process and then how could I automatically kill that process if it was on the 'approved kill process' list?
A product from http://www.packettrap.com/ called PT360 would be perfect except they use SMNP to get data and SMNP appears to only give total CPU usage, it's not broken out by an individual core. Take a look at their Dashboard option with the CPU gauge 'gadget'. That's exactly what I need if only it worked at the core level.
Any ideas?
Individual CPU usage is available through the standard windows performance counters. You can monitor this in perfmon.
However, it won't give you the result you are looking for. Unless a thread/process has been explicitly bound to a single CPU then a run-away process will not spike one core to 100% while all the others idle. The run-away process will bounce around between all the processors. I don't know why windows schedules threads this way, presumably because there is no gain from forcing affinity and some loss due to having to handle interrupts on particular cores.
You can see this easily enough just in task manager. Watch the individual CPU graphs when you have a single compute bound process running.
You can give Spotlight on Windows a try. You can graphically drill into all sorts of performance and load indicators. Its freeware.
perfmon from Microsoft can monitor each individual CPU. perfmon also works remote and you can monitor farious aspects of Windows.
I'm not sure if it helps to find run-away processes because the Windows scheduler dos not execute a process always on the same CPU -> on your 8 CPU machine you will see 12.5 % usage on all CPU's if one process runs away.