memory – How can I reserve RAM on a server for RDP processes?

I manage a windows server that sometimes drops all RDP connections when the memory approaches its capacity. The server is more or less unreachable (see this question for details) until the RAM usage drops.

Can I place a virtual barrier on the overall RAM usage such that there’s always sufficient RAM left to keep at least one RDP session alive?

That session could then be used to kill the offending process and free up more RAM.

18.04 – What is the cause of these zombie processes?

I just ran top and found out 10 zombie processes in my ubuntu 18.04, which is running on the virtualBox. Then I ran top axjf and found that all of the 10 zombie processes were caused by this parent process:

1175  1176  1173  1173 ?           -1 Sl    1000   0:00  _ /usr/bin/VBoxClient --vmsvga-x11

And here are some examples of the defunct processes:

1176  1177  1173  1173 ?           -1 Z     1000   0:00      _ [sh] <defunct>
1176  1182  1173  1173 ?           -1 Z     1000   0:00      _ [sh] <defunct>

The other zombies just look similar to these two.

Please tell me the cause of these processes and how to kill them. Notify me if more details are expected to be provided.

memory – I need to run multiple processes at once, which server should I use

I bough droplet on DigitalOcean 1GB and 1CPU. I’m running cronjob there. Currently I’m able to run 30 background tasks(processes) at once, once I go up server cannot handle that much.

Those background processes are sending requests to an endpoint, collect a data to array and then send it to another endpoint. Each task process 100 data.

Can you help me choose the right server. I’d like to run at least 100 tasks(processes) in the background at once. Should I buy more RAM or CPU?

Here is current usage, I don’t see that server is overloaded with 40 tasks but it can’t handle it:
enter image description here

What am I doing wrong?

probability – The Definition of Entropy. Boltzmann/Shannon Entropy. The Heat Equation. Stochastic Processes.

Lets talk about Entropy, specifically the statistical mechanics interpretation of Entropy. Loosely speaking Entropy is described as a quantifier of how chaotic a system is. The more micro-states attainable by the system (with appreciable probability) the higher the Entropy of the system.

For example rolling a fair dice will be much more `chaotic’ than flipping a heavily weighted coin.

As far as I am aware Boltzmann Entropy and Shannon Entropy are defined similarly (differing only by a constant), Shannon Entropy of a system described by the random variable $X$ with mass function $p$ (resp. density) is :

$$H(X):=-sum_{i=1}^np(x_i)log(p(x_i))~~text{or in the continuous case }~~ H(X):=-int p(x)log p(x) dx.$$

For systems which are irreversible the 2nd law of Thermodynamics says entropy will always increase. Consider the case of dispersion of heat : Let $W_t,~tin(0,infty)$ be a Brownian Motion, the density $p_t$ of this stochastic process solves the heat equation :

$$ frac{dp}{dt}=Delta p $$

and the entropy of the system (at time $t$) is defined as $-int p_t(x) log p_t(x) dx$.

My $textbf{Question :}$ Consider a general stochastic process $Y_t$

$$dY_t:= u(Y_t)dW_t$$

(say for a convex function $u$) what justification do people have for calling the entropy of this process

$$ -int u(p_t)dx? $$

My thoughts : This so called `entropy’ has nothing to do with Boltzmann/Shannon Entropy, it is just a name used to describe a quantity of the system which should behave similarly to the usual definition entropy (i.e increase as time increases).

How are scientific research projects planned? In particular computer science, but possibly there exists processes for all research?

Possibly some context:
Take any research endeavor. Finding a vaccine. Going to the moon. Clean energy. I don’t have a background in these scientific areas so picking one closer to home (Comp Sci) might be better. But the idea is how to battle the Unknowns? How to do it economically? How to make progress while not getting analysis paralysis?

Some might suggest a scrum, or an agile process try to solve these questions. I’m not certain that they address the same level or kinds of Unknowns.

Are there previous experiences that work, and those that don’t work? And why? The questions grows on the way forward through unknowns, and by definition the Unknown doesn’t exactly have a road map, and new context is developed regularly.

This maybe simply the question of the ‘meta’ variety: Is there research on comp sci research? If so does Comp Sci research have approaches or techniques that they rely on?

stochastic processes – Decomposition of Gaussian spaces with respect to covariance function

Let $K(t,s):T^2 to mathbb{R}$ be a kernel symmetric and type positive (for every $n$ $sum^n_{i,j}u_iu_jK(t_i,t_j) geq 0$ and $(u_1,dots,u_n) in mathbb{R}^n$) where $T$ is any set. Thus, it is possible get a suitable probability space ($Omega, mathcal{F},P$) and a Gaussian process $(X_t)_{t in D}:Omega to mathbb{R}$ with values in $mathcal{H}$ (a closed subspace of $L^2(Omega, mathcal{F},P$) of Gaussian process with mean 0) and $K$ is the covariance function of $X_t$. I know that if I can write $X_t = Z^{1}_t + Z^2_t$ where $Z^{1}_t$ and $ Z^2_t$ are independent centered Gaussian processes then
$$K(t,s) = K_1(t,s) + K_2(t,s),$$
where $K_1$ and $K_2$ are the covariance function of $Z^{1}_t$ and $Z^2_t$ respectively. I’m asking for a converse of it: If I have $K(t,s) = K_1(t,s) + K_2(t,s)$, then I can get $Z^{1}_t$ and $ Z^2_t$ independent centered Gaussian processes. Thanks for any help.

stochastic processes – Mathematical expectation of the number of points for Poisson stohastic process

I need to find mathematical expectation of the number of points of Poisson process with parameter $lambda > 0$ such that: these points $in (1,2)$ and there are no points of Poisson process in their left $delta$ neighborhood, where $delta in (0,1)$.
What i mean is: find mathematical expectancy of the number of points such that:
for example: if a is the point, then there are not points of Poisson process in $(a – delta, a)$
and a should be in $(1,2)$

antivirus – Would an anti-virus software make any other processes consume more CPU?

Would an anti-virus software make any other processes that it scans to consume more CPU?

We recently switched to a new Next-Gen, AI based Anti-Virus software. On couple of our Linux servers that runs Java processes, there has been frequent high spikes in CPU usage recently. Apparently, it is Java that is the highest consumer of CPU while the anti-virus process isn’t using a lot. I am pretty sure that it is not the anti-virus behind the higher CPU usage since the these spikes started a couple of days before even the AV software was installed. So, right now, I am in the process on convincing others that it is not the anti-virus (trust me, no one is believing what they see at top -c) . Before I go back to the team, I would like to make sure that when anti-virus scans every single file that gets opened by other processes, the resultant CPU usage would show up against the anti-virus process and not against the process that opens the file. Is this how it will appear in CPU usage stats?

Server run Amazon Linux and the Anti-Virus is Crowdstrike Falcon.

how to write a function to show lists of running processes or while loop functions in php

Please i have a while loop function that am using to insert data into my database periodically, for some reasons i found out that while loop is more easy to use than cronjob, while loop runs without anyone having to visit the site, but my problem is that once a while loop is started it keeps running even if you delete the codes from your php file, it keeps running, and if you amend the code with new values and start it again both the old loop and the new one keeps running.
My question is how can i write a php function that will list out all current running loop processes in my webhost or server and then use another code to end or stop or remove it from running?

Below is my code

$date = date('Y-h-m H:i:s');
$counter = 0;
while($counter < 10){

    $wpdb->query("INSERT INTO a_boy (username, password) VALUES ('cash', $date)");
    $counter + 1;
    sleep(60);
}