What is the cause of hanging pages when extremely busy (1,400 online in the past 30 minutes)

[marklcfc]

Once my site reaches this amount, pages start to hang and sometimes take 20-30 seconds to load.

The load is only 2-3 and memory usage is only 45%.

Would it be the CPU not being able to process all the queries or is it a setting I can alter? The site copes with large amounts of traffic fine until it reaches that amount of activity.

[Rhett]

This is hard to say without running some test on your server.... but my first guess is going to be your disk i/o

Can you post up the specs on your server

CPU's make and model
RAM
Raid? if so which one
Hard drive specs? Sata? SAS?

If this is a linux box, which I will assume, do you have sysstat installed? if so run "sar" and paste up the output. If not, "yum install sysstat" then run it in after it has had a few minutes to gather data.

[marklcfc]

AMD Phenom II X4 840 Processor 4CPU

8GB RAM.

Linux.

Where would I find Raid and hard drive specs?

sar results

06:20:01 AM all 2.60 0.00 0.62 0.09 0.00 96.68
06:30:01 AM all 2.51 0.01 0.56 0.06 0.00 96.86
06:40:01 AM all 3.19 0.01 0.72 0.08 0.00 96.01
06:50:01 AM all 3.87 0.06 0.94 0.06 0.00 95.07
07:00:01 AM all 4.33 0.01 1.17 1.16 0.00 93.34
07:10:01 AM all 4.13 0.10 1.05 0.16 0.00 94.57
07:20:01 AM all 4.66 0.00 1.11 1.32 0.00 92.89

07:20:01 AM CPU %user %nice %system %iowait %steal %idle
07:30:01 AM all 5.91 0.01 1.33 0.26 0.00 92.49
07:40:01 AM all 7.65 0.01 1.71 0.41 0.00 90.22
07:50:01 AM all 7.44 0.06 1.73 0.40 0.00 90.37
08:00:01 AM all 7.82 0.00 1.76 0.18 0.00 90.24
08:10:01 AM all 11.14 0.01 2.55 0.25 0.00 86.06
08:20:01 AM all 8.34 0.01 1.88 0.23 0.00 89.54
08:30:01 AM all 9.33 0.00 2.17 0.18 0.00 88.32
08:40:01 AM all 9.53 0.00 2.20 0.16 0.00 88.10
08:50:01 AM all 8.68 0.06 2.04 0.15 0.00 89.07
09:00:01 AM all 11.14 0.01 2.35 0.19 0.00 86.32
09:10:01 AM all 11.21 0.17 2.48 0.19 0.00 85.95
09:20:01 AM all 9.84 0.00 2.25 0.20 0.00 87.70
09:30:02 AM all 10.70 0.00 2.46 0.15 0.00 86.70
09:40:01 AM all 10.65 0.00 2.48 0.19 0.00 86.68
09:50:01 AM all 11.85 0.06 2.77 0.18 0.00 85.14
10:00:01 AM all 14.88 0.01 3.07 0.53 0.00 81.52
10:10:01 AM all 17.24 0.00 3.69 0.17 0.00 78.90
10:20:01 AM all 16.86 0.01 3.81 0.22 0.00 79.10
10:30:01 AM all 17.19 0.00 3.81 0.23 0.00 78.77
10:40:01 AM all 17.55 0.00 3.76 0.22 0.00 78.47
10:50:01 AM all 18.16 0.07 4.05 0.25 0.00 77.48
11:00:01 AM all 18.09 0.01 4.05 0.25 0.00 77.60

11:00:01 AM CPU %user %nice %system %iowait %steal %idle
11:10:01 AM all 18.33 0.00 4.02 0.27 0.00 77.38
11:20:01 AM all 17.25 0.32 3.86 0.31 0.00 78.26
11:30:01 AM all 18.75 0.00 4.32 0.23 0.00 76.70
11:40:01 AM all 17.55 0.01 3.84 0.19 0.00 78.42
11:50:01 AM all 18.46 0.06 4.14 0.17 0.00 77.17
12:00:01 PM all 19.03 0.00 4.03 0.21 0.00 76.73
12:10:01 PM all 19.61 0.00 4.17 0.28 0.00 75.94
12:20:01 PM all 17.70 1.42 4.09 0.69 0.00 76.09
12:30:01 PM all 20.02 0.00 3.96 0.16 0.00 75.85
12:40:01 PM all 19.59 0.00 4.13 0.36 0.00 75.92
12:50:01 PM all 21.65 0.07 4.75 0.22 0.00 73.30
01:00:01 PM all 24.65 0.00 5.49 0.82 0.00 69.03
01:10:01 PM all 24.49 0.00 5.27 0.24 0.00 69.99
01:20:01 PM all 23.65 0.36 5.25 0.27 0.00 70.46
01:30:01 PM all 24.91 0.01 5.29 0.20 0.00 69.59
01:40:01 PM all 22.05 0.01 4.59 0.31 0.00 73.04
01:50:01 PM all 19.61 0.06 4.26 0.18 0.00 75.88
02:00:01 PM all 18.77 0.00 4.19 0.16 0.00 76.87
02:10:01 PM all 18.68 0.00 4.11 0.20 0.00 77.00
02:20:01 PM all 16.89 0.01 3.79 0.18 0.00 79.14
02:30:01 PM all 16.24 0.01 3.83 0.23 0.00 79.70
02:40:01 PM all 15.96 0.01 3.72 0.20 0.00 80.12

02:40:01 PM CPU %user %nice %system %iowait %steal %idle
02:50:01 PM all 17.60 0.06 4.09 0.20 0.00 78.05
03:00:01 PM all 20.64 0.00 4.52 0.22 0.00 74.62
03:10:01 PM all 22.60 0.01 5.04 0.22 0.00 72.13
03:20:01 PM all 20.11 0.35 4.32 0.22 0.00 75.00
03:30:01 PM all 19.64 0.00 4.07 0.25 0.00 76.04
03:40:01 PM all 19.07 0.00 4.21 0.21 0.00 76.51
03:50:01 PM all 16.32 0.06 3.60 0.22 0.00 79.81
04:00:01 PM all 17.40 0.00 3.79 0.13 0.00 78.68
04:10:01 PM all 18.06 0.00 3.84 0.19 0.00 77.90
04:20:01 PM all 20.95 0.01 4.39 0.19 0.00 74.46
04:30:01 PM all 21.89 0.00 4.58 0.22 0.00 73.30
04:40:01 PM all 20.66 0.01 4.42 0.20 0.00 74.71
04:50:01 PM all 20.84 0.06 4.55 0.26 0.00 74.29
05:00:01 PM all 22.04 0.00 4.55 0.29 0.00 73.11
05:10:01 PM all 22.93 0.33 4.71 0.30 0.00 71.73
05:20:01 PM all 25.28 0.00 5.39 0.27 0.00 69.06
05:30:01 PM all 23.02 0.00 4.94 0.25 0.00 71.79
05:40:01 PM all 23.78 0.00 5.04 0.26 0.00 70.92
05:50:01 PM all 23.91 0.06 5.08 0.26 0.00 70.68
06:00:01 PM all 25.89 0.01 5.15 0.20 0.00 68.74
06:10:01 PM all 23.21 0.00 4.89 0.20 0.00 71.69
06:20:01 PM all 22.67 0.01 4.80 0.30 0.00 72.22

06:20:01 PM CPU %user %nice %system %iowait %steal %idle
06:30:01 PM all 25.02 0.01 5.30 0.28 0.00 69.39
06:40:01 PM all 31.45 0.01 6.24 0.27 0.00 62.03
06:50:01 PM all 34.40 0.06 6.70 0.28 0.00 58.56
07:00:01 PM all 36.91 0.00 6.99 0.31 0.00 55.78
07:10:01 PM all 35.15 0.48 6.64 0.24 0.00 57.48
07:20:02 PM all 39.18 0.00 7.04 0.23 0.00 53.55
07:30:01 PM all 35.93 0.00 6.70 0.30 0.00 57.07
07:40:01 PM all 36.21 0.01 6.72 0.19 0.00 56.87
07:50:01 PM all 38.43 0.06 7.15 0.22 0.00 54.13
08:00:01 PM all 35.90 0.00 7.08 0.26 0.00 56.75
08:10:01 PM all 37.96 0.01 7.27 0.27 0.00 54.50
08:20:01 PM all 34.46 0.00 6.73 0.38 0.00 58.42
08:30:01 PM all 28.93 0.01 4.32 0.22 0.00 66.52
08:40:01 PM all 27.28 0.01 3.55 0.18 0.00 68.99
08:50:01 PM all 25.57 0.06 3.25 0.19 0.00 70.93
09:00:01 PM all 27.17 0.01 3.70 0.34 0.00 68.79
09:10:01 PM all 21.15 0.70 3.70 0.26 0.00 74.18
09:20:01 PM all 28.48 0.01 3.69 0.20 0.00 67.63
09:30:01 PM all 26.34 0.00 3.45 0.16 0.00 70.05
09:40:01 PM all 27.21 0.01 3.49 0.21 0.00 69.09
09:50:01 PM all 25.12 0.06 3.36 0.22 0.00 71.24
10:00:01 PM all 23.32 0.00 3.44 0.19 0.00 73.05

10:00:01 PM CPU %user %nice %system %iowait %steal %idle
10:10:01 PM all 21.54 0.01 3.17 0.28 0.00 75.00
10:20:01 PM all 21.00 0.00 3.18 0.19 0.00 75.63
10:30:01 PM all 17.94 0.00 2.99 0.19 0.00 78.88
10:40:01 PM all 24.30 0.00 5.40 0.53 0.00 69.77
10:50:01 PM all 19.61 0.06 4.53 0.39 0.00 75.41
11:00:01 PM all 19.88 0.01 4.62 0.31 0.00 75.19
11:10:01 PM all 22.54 0.00 5.07 0.40 0.00 71.98
11:20:01 PM all 20.72 0.60 4.67 0.19 0.00 73.82
Average: all 15.52 0.17 3.20 0.76 0.00 80.35

[Rhett]

Actually those numbers don't look bad at all on the io... but typically I see that issue around those numbers online with a normal 7200rpm sata... so that was my first guess without looking.

Looking at this... it looks that your slowdowns were happening between 6-10pm? is this right?

Without more info... looking at the above... your processor is the weak link here... it's a low end desktop processor and that's about all you can expect of it to be honest.

[marklcfc]

Yeah, between 6-10pm was when the site got really busy.

I had noticed memory_limit is at 64M, would increasing it to 128M make any difference?

Or do I need to upgrade my processor as RAM and server load are always fine.

[Rhett]

128mb is recommended, but if it's not throwing errors that's not going to help any really.. 8gb of ram is fine, but the processor is the weak link... upgrade that if you can and you should be good for a while.

[marklcfc]

My host said they could upgrade to a hex core, how much would that improve matters? (I don't know much about processors)

[marklcfc]

AMD's Six-Core Phenom II X6, is that a big improvement on what I have?

[AndyF]

AMD's Six-Core Phenom II X6

, is that a big improvement on what I have?

That's a desktop processor though really rather than a server one such as Opteron. Having said that I have a X6 1100T in my desktop and its quite powerful.