a few days ago my Apache server randomly started hogging the CPU during which time the site becomes sluggish and unresponsive.   Here is what mod_status shows during an incident:   Nearly all connections are in the waiting state A few connections are in the Keep-Alive state. All of them have Req column values (Milliseconds required to process most recent request) between 15 and 40 seconds, which is 10-20x longer than usual During this time, running top command shows 100% usage of all 4 CPUs, with 5-7 Apache child processes on top, taking 10-40% percent CPU each   Each incident lasts 15-30 minutes and then the situation returns to normal for a while, until another incident occurs.   Server configuration and stats:   Digital Ocean droplet with 4 CPU's, 8 GB RAM LAMP stack running a Wordpress site, about 40K hits per day (XMLRPC protected, wp-login protected) MySQL performance appears normal (slow query logging on, nothing unusual)   Any advice on debugging this would be appreciated as I don't even know where to start.     Server Version: Apache/2.4.7 (Ubuntu) PHP/5.5.9-1ubuntu4.11 Server MPM: prefork Server Built: Jul 24 2015 17:25:11 Current Time: Sunday, 02-Oct-2016 08:41:09 EDT Restart Time: Sunday, 02-Oct-2016 07:55:53 EDT Parent Server Config. Generation: 1 Parent Server MPM Generation: 0 Server uptime: 45 minutes 15 seconds Server load: 105.26 38.36 22.87 Total accesses: 32705 - Total Traffic: 367.2 MB CPU Usage: u455.08 s51.66 cu0 cs0 - 18.7% CPU load 12 requests/sec - 138.5 kB/second - 11.5 kB/request 144 requests currently being processed, 39 idle workers _WWWWWWWWW_WKWWWWW__WWWW._WW.WWWW___W.WWWW__WWW_W_WWWW_WW.W_WWWW _W.WCWW_WW.WKWWWWWWWWW_WWWKW.W_K_.KW__K.W._WWWWW__WWWWWWWWW._WKW WWWK.WW_WW__WWWWWWWW__WWW_WWWW_WWWWWW_._WWWKK___WWW_WWWWWWWWWWWW _.W..WW. Scoreboard Key: "_" Waiting for Connection, "S" Starting up, "R" Reading Request, "W" Sending Reply, "K" Keepalive (read), "D" DNS Lookup, "C" Closing connection, "L" Logging, "G" Gracefully finishing, "I" Idle cleanup of worker, "." Open slot with no current process
We have Godaddy's Dedicated server. but we are facing problems with this server. after on 400-500 active users server randomly timeout or kill users. we this it's error with IIS. We did conversation with some server experts they said there is some issue with IIS. but nobody can resolve this issue. i share a screen shoot of analytic of active users. Please help us.
Contraction Map on Compact Normed Space has a Fixed Point Is there a word to describe the virtue of "to do something and ask for nothing in return"? I am wondering if there is a positive, formal counterpart to the slang "No strings attached" to describe, for example, a parent's unquestioned devotion to their children, or the virtue of someone's "a friend in need is a friend in deed", help first, question later mentality. Differentiation operator and eigenvalues Let $V = \{p(x) \in F[x] \ | \ \deg(p(x)) \le n\}$. Let $T : V \to V$ be given by differentiation, in essence $$T(p(x)) = p'(x)$$ It seems to me that the only eigenvalue that can exist is $\lambda =0$, since the given operator lowers the degree of any given polynomial and hence makes it impossible for a constant multiple of a polynomial to be equal to the polynomial's derivative. Is my claim correct? Let $\alpha = \frac{1+\sqrt{-19}}{2}$. Let $A = \mathbb Z[\alpha]$. Let's assume that we know that its invertibles are $\{1,-1\}$. During an exercise we proved that:     Lemma: If $(D,g)$ is a Euclidean domain such that its invertibles are $\{1,-1\}$, and $x$ is an element of minimal degree among the elements that are not invertible, then $D/(x)$ is isomorphic to $\mathbb Z/2\mathbb Z$ or $\mathbb Z/3\mathbb Z$.   Now the exercise asks:     Prove that $A$ is not a Euclidean Domain.   Everything hints to an argument by contradiction: let $(A, d)$ be a ED and $x$ an element of minimal degree among the non invertibles we'd like to show that $A/(x)$ is not isomorphic to $\mathbb Z/2\mathbb Z$ or $\mathbb Z/3\mathbb Z$.  How do we do that? My problem is that, since I don't know what this degree function looks like, I don't know how to choose this $x$!  I know that the elements of $A/(x)$ are of the form $a+(x)$, with $a$ of degree less than $x$ or zero. By minimality of $x$ this means that $a\in \{0, 1, -1\}$. Now I'm lost: how do we derive a contradiction from this? Windows 7's PATH and environment variables are corrupted Kinetic energy conservation in collision.  In any type of collision type of collision if we take the system to comprised of both bodies then the net external force is zero. So the work done by external force is also zero. By the relation $W=K_f-K_i$ as $W$ is zero hence kinetic energy is conserved. But this not the case.   Can you tell me what is the flaw in my argument? Some people say that the argument has neglected the fact that some kinetic energy is transformed into heat. But heat is created due to the interactions between bodies during collision which is thus an internal force and thus shouldn't affect kinetic energy. Which is better: ... or ... find() function in python2.7.5 How do you change age settings on ROBLOX? How do you set your age settings on ROBLOX if you accidentally set to under 13? I accidentally put 2008 instead of 1998 in the sign up section. Is there any way to change this, as in settings, age settings are greyed out. (Sorry to re-post this, I have lost access to my original account.)  I've recently installed Kubuntu 18.04.3 on a new AMD Ryzen 3000-series-based system. The system is installed on a SATA SSD, specifically on an Ext4 partition, with a SATA HDD formatted in NTFS mounted for storage. The system has been in use for a few days, with a maximum uptime of two days (so far).  My issue is this: the HDD indicator light on the case flashes every 1-3 seconds, even when the system is idle, and there is no obvious reason to access the disk. The flashes are not regular: sometimes the light is dark for as long as 3 seconds (obviously it is difficult to time such short intervals -- I am approximating), sometimes there are a few quick pulses less than a second apart. The flashes seem to vary in duration as well -- sometimes very brief, sometimes nearly a second. Unmounting the secondary HDD does not appear to have any effect.  Some searching lead me to try iotop. I ran sudo iotop -Pao, and waited until 10 flashes of the HDD light had occurred. This is the result:   6887 be/4 root          0.00 B      0.00 B  0.00 %  0.02 % [kworker/u64:1-events_power_efficient]   433 be/3 root          0.00 B      0.00 B  0.00 %  0.02 % [jbd2/sda2-8]  6302 be/4 root          0.00 B      0.00 B  0.00 %  0.01 % [kworker/u64:0-events_unbound]   The "kworker" processes seem to switch between various states, such as "events_power_efficient", "events_unbound", and "events_freezable_power_". The jdb2 process does sometimes write to disk, though that was not observed here (even though, as I said, 10 flashes of the HDD light occurred). The computer was otherwise idle during this test.  My searches also lead me to check /var/log. The result of ls -lth | head is as follows:  -rw-r-----  1 syslog adm             951K Aug 27 19:49 kern.log -rw-r-----  1 syslog adm             594K Aug 27 19:49 syslog -rw-r-----  1 syslog adm             528K Aug 27 19:49 ufw.log -rw-r-----  1 syslog adm              53K Aug 27 19:48 auth.log -rw-r--r--  1 root   root             40K Aug 27 19:15 Xorg.0.log -rw-rw-r--  1 root   utmp             79K Aug 27 18:29 wtmp -rw-r--r--  1 root   root              55 Aug 27 16:28 prime-offload.log -rw-r--r--  1 root   root              30 Aug 27 16:28 prime-supported.log -rw-r--r--  1 root   root            1.2K Aug 27 16:28 gpu-manager.log   I have no experience interpreting log files, so I don't know if anything here is out of the ordinary.  If the kernel version is relevant, the output of uname -r is 5.0.0-25-generic.  My questions are, 1. Why is my HDD light flashing, even though there is no obvious disk activity, 2. Does this indicate some kind of problem with my system that needs to be fixed, and 3. If so, how do I fix it? The light itself does not bother me -- if this is just a sign of a normal, healthy Ubuntu install, then no problem. My concern is that something is wrong, and if so, I would like to fix it.  Thanks in advance for your time.  In response to heynnema (in the original posting of this question), the issue occurs even at the log-in screen, before I log in. So, it is not tied to my user account. However, it does not occur in the BIOS, suggesting that it is specific to Kubuntu (or at least, to the SSD Kubuntu is installed on). Is there a term for the moment when a lot of users visit/log onto your website at the same time? Is there a term for the moment when a lot of users visit/log onto your website at the same time? Can I install Microsoft Office? If so, how? translation invariant of integral on $\mathbb{R}$ Problem 1: Let $f\in L^1(\mathbb{R})$, show $\int_\mathbb{R}f(t)dt=\int_{\mathbb{R}}f(x+t)dt,\forall x\in (-\infty, \infty)$.  Problem 2: Let $f\in L^1(\mathbb{R})$,show $\displaystyle \lim_{t\rightarrow 0}\int_{\mathbb{R}}|f(x+t)-f(x)|dx=0$.  My try for Problem 1:  Consider $\displaystyle \int_{\mathbb{R}}f(t)dt=\lim_{n\rightarrow \infty}\int_{-n}^nf(t)dt=\lim_{n\rightarrow \infty}\int_{\mathbb{R}}f_n(t)dt$, where $f_n(t)=f(t)\chi_{[-n,n]}$.  And since $dt=d(x+t)$, we have $\displaystyle \int_{-n}^nf(x+t)dt=\int_{-n+x}^{n+x}f(t)dt$.  So for each $x\in (-\infty,\infty)$,  $$ \begin{split} \int_{\mathbb{R}}f(t)-f(t+x)dt &amp;=\lim_{n\rightarrow \infty}\int_{\mathbb{R}}f(t)(\chi_{[-n,n]}-\chi_{[-n+x,n+x]})dt\\ &amp;=\lim_{n\rightarrow \infty}\int_{\mathbb{R}}f(t)(\chi_{[-n,-n+x]}-\chi_{[n,n+x]})dt\\ &amp;=\lim_{n\rightarrow \infty}\lim_{k\rightarrow \infty}\int_\mathbb{R}\varphi_k(t)(\chi_{[-n,-n+x]}-\chi_{[n,n+x]})dt\\ &amp;=\lim_{k\rightarrow \infty}\lim_{n\rightarrow \infty}\int_\mathbb{R}\varphi_k(t)(\chi_{[-n,-n+x]}-\chi_{[n,n+x]})dt \end{split} $$ where $\varphi_k(t)$ is simple function pointwise converges to $f(t)$, simple function vanish out of set of finite measure, so $\varphi_k(t)(\chi_{[-n,-n+x]}-\chi_{[n,n+x]})$ vanishes when $n$ big enough(is this right?)    Another try:  Since $f\in L^1$, $f$ is bounder a.e. so can be approximated by simple functions, and $\chi_{A+t}(x)=\chi_A(x-t)$,thus $$\int f(t)=\lim_n\int\varphi_n=\lim_n \sum_{i=1}^nc_i\mu(E_i)=\lim_n \sum_{i=1}^nc_i\mu(E_i-x)=\int f(t+x)$$  For problem 2, I guess they share the same method.   Any help or correction about these two problems? Thanks. Hi I have to proof that for $\Omega$ a nested family of odd subsets of $V$ with $V$ finite, we have that $|\Omega|\leq\frac{3}{2}|V|$. I can prove that for certain constructions of $\Omega$, it is satisfies $|\Omega|\leq \frac{3}{2} |V|$, the problem I encounter is that I have to proof that my construction of $\Omega$ is optimal. (Since I have to prove that this holds for every family of odd subsets) Can anyone give me a hint on how to proof that every $\Omega$ satisfies this equation.    $\Omega$ is nested if for all $A,B\in\Omega$ either $A\subseteq B$, $B\subseteq A$, or $A\cap B=\varnothing$; a set is odd if its cardinality is odd. Let $A \in Mat_{n \times n}(F)$ a matrix which satisfies $A^n=0$ and $A^{n-1} \ne 0$ for some positive integer $n$. Let $v \in F^n$ be such that $A^{n-1}v \ne 0$.  Prove that $\{v, Av, A^2v,...,A^{n-1}v\}$ is a basis for $F^n$.     So, from definition of $A$, I know that $A^iv \ne 0$ for all $0\le i \le n-1$. I know I need to prove the set is linearly independent and span $F^n$ to prove it's a basis, but I just don't know how. Assume $0 &lt; a_0 \leq a_1 \leq \cdots \leq a_n$, show that equation   $$ p_n(z) = a_0 z^n + a_1 z^{n-1} + \cdots + a_{n-1} z + a_n = 0 $$   does not have root in $|z| &lt; 1$. Here $z$ is complex.   I started by considering the case in which $n = 2$, and tried to use the triangle inequality, while no progress was made. Any hints will be appreciated. Is spell level a character concept or a player concept? Is there anything in RAW that supports spell level as a character concept, or alternatively that supports it as solely a player concept?  On the one hand, I see nothing that explicitly states that a character knows that there are spell levels. On the other hand, I don't see how a spellcaster could manage spell slots without knowing about spell levels. Distribution of the maximum of two correlated normal variables In my device (iPhone 6, iOS v8.0.2, app v1.2.0.138) whenever I receive a notification and I tap it in order to open the application, the screen that is displayed is blank.  I need to quit the app, re-open it, go to my 'inbox' and tap the last notification in order to see the question screen, focused on the comment.  This is not new (for me) in v1.2.0.138; it has been happening for at least the last ~7 updates that I've done. How does LSTM prevent the vanishing gradient problem? LSTM was invented specifically to avoid the vanishing gradient problem. It is supposed to do that with the Constant Error Carousel (CEC), which on the diagram below (from ) correspond to the loop around cell.  (source: ) And I understand that that part can be seen as a sort of identity function, so the derivative is one and the gradient stays constant. What I don't understand is how it does not vanish due to the other activation functions ? The input, output and forget gates use a sigmoid, which derivative is at most 0.25, and g and h were traditionally tanh. How does backpropagating through those not make the gradient vanish ?