I have an issue I cannot get to grips with. We have an app server that has mysteriously started "dropping requests". These are ajax requests.

I restart php5-fpm, all runs fine for a few minutes then the success rate degrades over the subsequent hours. When there is a certain load, the ajax connexion come back .. not truncated, but empty of their payload.

I am out of ideas on how to tackle this, I am not often faced with these type of issues.

  • Server has 128M of ram
  • 24 CPU's,

Here is Nginx.conf, buffer configuration and fastcgi_temp_path was added, but nothing is written to the /tmp directory.

user www-data;
worker_processes 4;
pid /run/nginx.pid;

events {
    worker_connections 768;
    # multi_accept on;

http {

         client_body_buffer_size     100m;
         client_max_body_size        100m;

        # proxy buffer settings
        proxy_buffer_size   1020k;
        proxy_buffers   256 4k;
        proxy_busy_buffers_size   1020k;
        fastcgi_temp_path /tmp/nginx_fastcgi;
    # Basic Settings

        ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
        ssl_dhparam /etc/nginx/ssl/dhparam.pem;
        # L'ECDHE sera proposé au navigateur par l'ajout de HIGH dans la directive ssl_ciphers
        ssl_ciphers "HIGH:!aNULL:!MD5:!ADH:!RC4:!DH";

        # La directive ssl_prefer_server_ciphers permet de forcer le navigateur à utiliser les préférences de chiffrement du serveur
        # Sans cette directive, le Perfect Forward Secrecy risque de ne pas être activé car l'ECDHE ne sera pas proposé en premier
        ssl_prefer_server_ciphers on;

    sendfile on;
    tcp_nopush on;
    tcp_nodelay on;
    keepalive_timeout 65;
    types_hash_max_size 2048;
    # server_tokens off;

    # server_names_hash_bucket_size 64;
    # server_name_in_redirect off;

    include /etc/nginx/mime.types;
    default_type application/octet-stream;

    # Logging Settings

    access_log /var/log/nginx/access.log;
    error_log /var/log/nginx/error.log;

    # Gzip Settings

    # Enable gzip compression.
    gzip on;
    gzip_disable "msie6";

    # Compression level (1-9).
    # 5 is a perfect compromise between size and CPU usage, offering about
    # 75% reduction for most ASCII files (almost identical to level 9).
    gzip_comp_level 5;

    # Don't compress anything that's already small and unlikely to shrink much
    # if at all (the default is 20 bytes, which is bad as that usually leads to
    # larger files after gzipping).
    gzip_min_length 256;

    # Compress data even for clients that are connecting to us via proxies,
    # identified by the "Via" header (required for CloudFront).
    gzip_proxied any;

    # Tell proxies to cache both the gzipped and regular version of a resource
    # whenever the client's Accept-Encoding capabilities header varies;
    # Avoids the issue where a non-gzip capable client (which is extremely rare
    # today) would display gibberish if their proxy gave them the gzipped version.
    gzip_vary on;

    # Compress all output labeled with one of the following MIME-types.
        # text/html is always compressed by gzip module

    # Virtual Host Configs

    upstream papp {
        server unix:/var/run/php5-fpm-papp.sock; #for PHP-FPM running on UNIX socket

    #fastcgi_cache_path /etc/nginx/cache levels=1:2 keys_zone=MYAPP:100m inactive=60m;
    #fastcgi_cache_key "$scheme$request_method$host$request_uri";

    include /etc/nginx/conf.d/*.conf;
    include /etc/nginx/sites-enabled/*;

Here is the vhost:

server {
    # set the user that runs nginx & php
    set $phpfcgi papp;

    listen 80;
    listen 443 default_server ssl;

    server_name compte.papp.com;
    root /var/www/papp.com/prod/web;

    #ssl on;
    ssl_certificate     /etc/nginx/ssl/papp.com/2018-12-03/compte.pretinstant.com.combined.crt;
    ssl_certificate_key /etc/nginx/ssl/papp.com/2018-12-03/compte.papp.com.key;

    error_log  /var/log/nginx/papp.com.compte.error.log notice;
    access_log /var/log/nginx/papp.com.compte.access.log;
    #rewrite_log on;

    client_body_buffer_size     100m;
    client_max_body_size        100m;

    # strip app.php/ prefix if it is present
    rewrite ^/app\.php/?(.*)$ /$1 permanent;

    location / {
        index app.php;
        try_files $uri @rewriteapp;

    location @rewriteapp {
        rewrite ^(.*)$ /app.php/$1 last;

    # pass the PHP scripts to FastCGI server from upstream phpfcgi
    #location ~ ^/(app|app_dev|config)\.php(/|$) {
    location ~ ^/(app|app_dev|config|js/tinymce/plugins/moxiemanager/api)\.php(/|$) {

       # Set fastcgi buffer size
        #fastcgi_buffers 32 32k;
        #fastcgi_buffer_size 32k;

        fastcgi_pass $phpfcgi;
        fastcgi_split_path_info ^(.+\.php)(/.*)$;
        include fastcgi_params;
        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
        #fastcgi_param HTTPS on;


Here is php.conf:

; FPM Configuration ;

; All relative paths in this configuration file are relative to PHP's install
; prefix (/usr). This prefix can be dynamically changed by using the
; '-p' argument from the command line.

; Include one or more files. If glob(3) exists, it is used to include a bunch of
; files from a glob(3) pattern. This directive can be used everywhere in the
; file.
; Relative path can also be used. They will be prefixed by:
;  - the global prefix if it's been set (-p argument)
;  - /usr otherwise

; Global Options ;

; Pid file
; Note: the default prefix is /var
; Default Value: none
pid = /var/run/php5-fpm.pid

; Error log file
; If it's set to "syslog", log is sent to syslogd instead of being written
; in a local file.
; Note: the default prefix is /var
; Default Value: log/php-fpm.log
error_log = /var/log/php/php5-fpm.log

; syslog_facility is used to specify what type of program is logging the
; message. This lets syslogd specify that messages from different facilities
; will be handled differently.
; See syslog(3) for possible values (ex daemon equiv LOG_DAEMON)
; Default Value: daemon
;syslog.facility = daemon

; syslog_ident is prepended to every message. If you have multiple FPM
; instances running on the same server, you can change the default value
; which must suit common needs.
; Default Value: php-fpm
;syslog.ident = php-fpm

; Log level
; Possible Values: alert, error, warning, notice, debug
; Default Value: notice
;log_level = notice

; If this number of child processes exit with SIGSEGV or SIGBUS within the time
; interval set by emergency_restart_interval then FPM will restart. A value
; of '0' means 'Off'.
; Default Value: 0
;emergency_restart_threshold = 0

; Interval of time used by emergency_restart_interval to determine when
; a graceful restart will be initiated.  This can be useful to work around
; accidental corruptions in an accelerator's shared memory.
; Available Units: s(econds), m(inutes), h(ours), or d(ays)
; Default Unit: seconds
; Default Value: 0
;emergency_restart_interval = 0

; Time limit for child processes to wait for a reaction on signals from master.
; Available units: s(econds), m(inutes), h(ours), or d(ays)
; Default Unit: seconds
; Default Value: 0
;process_control_timeout = 0

; The maximum number of processes FPM will fork. This has been design to control
; the global number of processes when using dynamic PM within a lot of pools.
; Use it with caution.
; Note: A value of 0 indicates no limit
; Default Value: 0
; process.max = 128

; Specify the nice(2) priority to apply to the master process (only if set)
; The value can vary from -19 (highest priority) to 20 (lower priority)
; Note: - It will only work if the FPM master process is launched as root
;       - The pool process will inherit the master process priority
;         unless it specified otherwise
; Default Value: no set
; process.priority = -19

; Send FPM to background. Set to 'no' to keep FPM in foreground for debugging.
; Default Value: yes
;daemonize = yes

; Set open file descriptor rlimit for the master process.
; Default Value: system defined value
;rlimit_files = 1024

; Set max core size rlimit for the master process.
; Possible Values: 'unlimited' or an integer greater or equal to 0
; Default Value: system defined value
;rlimit_core = 0

; Specify the event mechanism FPM will use. The following is available:
; - select     (any POSIX os)
; - poll       (any POSIX os)
; - epoll      (linux >= 2.5.44)
; - kqueue     (FreeBSD >= 4.1, OpenBSD >= 2.9, NetBSD >= 2.0)
; - /dev/poll  (Solaris >= 7)
; - port       (Solaris >= 10)
; Default Value: not set (auto detection)
;events.mechanism = epoll

; When FPM is build with systemd integration, specify the interval,
; in second, between health report notification to systemd.
; Set to 0 to disable.
; Available Units: s(econds), m(inutes), h(ours)
; Default Unit: seconds
; Default value: 10
;systemd_interval = 10

; Pool Definitions ;

; Multiple pools of child processes may be started with different listening
; ports and different management options.  The name of the pool will be
; used in logs and stats. There is no limitation on the number of pools which
; FPM can handle. Your system will tell you anyway :)

; To configure the pools it is recommended to have one .conf file per
; pool in the following directory:

Here is the pool.d/papp.conf, in a gist since I busted caracter limit:


Your Answer

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Browse other questions tagged or ask your own question.